Use the following sheet to help remind you of how IP ranges break out. In otherwords, can you start a /30 network at 1.0.0.52, 1.0.0.54, or 1.0.0.56? (it's only .52) This sheet should help you visiualise that.

(note that you also could simply use the web verison of ipcalc or install it on your unix host. )

There is also an attached excel version of the following table.

2nd Octect:
CIDR	/15	/14	/13	/12	/11	/10	/9	/8
MASK	254	252	248	240	224	192	128	0
3rd Octect:
CIDR	/23	/22	/21	/20	/19	/18	/17	/16
MASK	254	252	248	240	224	192	128	0
4th Octect:
CIDR	/32 -/31	/30	/29	/28	/27	/26	/25	/24
MASK	255-254	252	248	240	224	192	128	0
0		0	0	0	0	0	0	0
1		|	|	|	|	|	|	|
|			|	|	|	|	|	|
2		|	|	|	|	|	|	|
3		3	|	|	|	|	|	|
|				|	|	|	|	|
4		4	|	|	|	|	|	|
5		|	|	|	|	|	|	|
|			|	|	|	|	|	|
6		|	|	|	|	|	|	|
7		7	7	|	|	|	|	|
|					|	|	|	|
8		8	8	|	|	|	|	|
9		|	|	|	|	|	|	|
|			|	|	|	|	|	|
10		|	|	|	|	|	|	|
11		11	|	|	|	|	|	|
|				|	|	|	|	|
12		12	|	|	|	|	|	|
13		|	|	|	|	|	|	|
|			|	|	|	|	|	|
14		|	|	|	|	|	|	|
15		15	15	15	|	|	|	|
|						|	|	|
16		16	16	16	|	|	|	|
17		|	|	|	|	|	|	|
|			|	|	|	|	|	|
18		|	|	|	|	|	|	|
19		19	|	|	|	|	|	|
|				|	|	|	|	|
20		20	|	|	|	|	|	|
21		|	|	|	|	|	|	|
|			|	|	|	|	|	|
22		|	|	|	|	|	|	|
23		23	23	|	|	|	|	|
|					|	|	|	|
24		24	24	|	|	|	|	|
25		|	|	|	|	|	|	|
|			|	|	|	|	|	|
26		|	|	|	|	|	|	|
27		27	|	|	|	|	|	|
|				|	|	|	|	|
28		28	|	|	|	|	|	|
29		|	|	|	|	|	|	|
|			|	|	|	|	|	|
30		|	|	|	|	|	|	|
31		31	31	31	31	|	|	|
|							|	|
32		32	32	32	32	|	|	|
33		|	|	|	|	|	|	|
|			|	|	|	|	|	|
34		|	|	|	|	|	|	|
35		35	|	|	|	|	|	|
|				|	|	|	|	|
36		36	|	|	|	|	|	|
37		|	|	|	|	|	|	|
|			|	|	|	|	|	|
38		|	|	|	|	|	|	|
39		39	39	|	|	|	|	|
|					|	|	|	|
40		40	40	|	|	|	|	|
41		|	|	|	|	|	|	|
|			|	|	|	|	|	|
42		|	|	|	|	|	|	|
43		43	|	|	|	|	|	|
|				|	|	|	|	|
44		44	|	|	|	|	|	|
45		|	|	|	|	|	|	|
|			|	|	|	|	|	|
46		|	|	|	|	|	|	|
47		47	47	47	|	|	|	|
|						|	|	|
48		48	48	48	|	|	|	|
49		|	|	|	|	|	|	|
|			|	|	|	|	|	|
50		|	|	|	|	|	|	|
51		51	|	|	|	|	|	|
|				|	|	|	|	|
52		52	|	|	|	|	|	|
53		|	|	|	|	|	|	|
|			|	|	|	|	|	|
54		|	|	|	|	|	|	|
55		55	55	|	|	|	|	|
|					|	|	|	|
56		56	56	|	|	|	|	|
57		|	|	|	|	|	|	|
|			|	|	|	|	|	|
58		|	|	|	|	|	|	|
59		59	|	|	|	|	|	|
|				|	|	|	|	|
60		60	|	|	|	|	|	|
61		|	|	|	|	|	|	|
|			|	|	|	|	|	|
62		|	|	|	|	|	|
63		63	63	63	63	63	|	|
|								|
64		64	64	64	64	64	|	|
65		|	|	|	|	|	|	|
|			|	|	|	|	|	|
66		|	|	|	|	|	|	|
67		67	|	|	|	|	|	|
|				|	|	|	|	|
68		68	|	|	|	|	|	|
69		|	|	|	|	|	|	|
|			|	|	|	|	|	|
70		|	|	|	|	|	|	|
71		71	71	|	|	|	|	|
|					|	|	|	|
72		72	72	|	|	|	|	|
73		|	|	|	|	|	|	|
|			|	|	|	|	|	|
74		|	|	|	|	|	|	|
75		75	|	|	|	|	|	|
|				|	|	|	|	|
76		76	|	|	|	|	|	|
77		|	|	|	|	|	|	|
|			|	|	|	|	|	|
78		|	|	|	|	|	|	|
79		79	79	79	|	|	|	|
|						|	|	|
80		80	80	80	|	|	|	|
81		|	|	|	|	|	|	|
|			|	|	|	|	|	|
82		|	|	|	|	|	|	|
83		83	|	|	|	|	|	|
|				|	|	|	|	|
84		84	|	|	|	|	|	|
85		|	|	|	|	|	|	|
|			|	|	|	|	|	|
86		|	|	|	|	|	|	|
87		87	87	|	|	|	|	|
|					|	|	|	|
88		88	88	|	|	|	|	|
89		|	|	|	|	|	|	|
|			|	|	|	|	|	|
90		|	|	|	|	|	|	|
91		91	|	|	|	|	|	|
|				|	|	|	|	|
92		92	|	|	|	|	|	|
93		|	|	|	|	|	|	|
|			|	|	|	|	|	|
94		|	|	|	|	|	|	|
95		95	95	95	95	|	|	|
|							|	|
96		96	96	96	96	|	|	|
97		|	|	|	|	|	|	|
|			|	|	|	|	|	|
98		|	|	|	|	|	|	|
99		99	|	|	|	|	|	|
|				|	|	|	|	|
100		100	|	|	|	|	|	|
101		|	|	|	|	|	|	|
|			|	|	|	|	|	|
102		|	|	|	|	|	|	|
103		103	103	|	|	|	|	|
|					|	|	|	|
104		104	104	|	|	|	|	|
105		|	|	|	|	|	|	|
|			|	|	|	|	|	|
106		|	|	|	|	|	|	|
107		107	|	|	|	|	|	|
|				|	|	|	|	|
108		108	|	|	|	|	|	|
109		|	|	|	|	|	|	|
|			|	|	|	|	|	|
110		|	|	|	|	|	|	|
111		111	11	111	|	|	|	|
|						|	|	|
112		112	112	112	|	|	|	|
113		|	|	|	|	|	|	|
|			|	|	|	|	|	|
114		|	|	|	|	|	|	|
115		115	|	|	|	|	|	|
|				|	|	|	|	|
116		116	|	|	|	|	|	|
117		|	|	|	|	|	|	|
|			|	|	|	|	|	|
118		|	|	|	|	|	|	|
119		119	119	|	|	|	|	|
|					|	|	|	|
120		120	120	|	|	|	|	|
121		|	|	|	|	|	|	|
|			|	|	|	|	|	|
122		|	|	|	|	|	|	|
123		123	|	|	|	|	|	|
|				|	|	|	|	|
124		124	|	|	|	|	|	|
125		|	|	|	|	|	|	|
|			|	|	|	|	|	|
126		|	|	|	|	|	|	|
127		127	127	127	127	127	127	|
|
128		128	128	128	128	128	128	|
129		|	|	|	|	|	|	|
|			|	|	|	|	|	|
130		|	|	|	|	|	|	|
131		131	|	|	|	|	|	|
|				|	|	|	|	|
132		132	|	|	|	|	|	|
133		|	|	|	|	|	|	|
|			|	|	|	|	|	|
134		|	|	|	|	|	|	|
135		135	135	|	|	|	|	|
|					|	|	|	|
136		136	136	|	|	|	|	|
137		|	|	|	|	|	|	|
|			|	|	|	|	|	|
138		|	|	|	|	|	|	|
139		139	|	|	|	|	|	|
|				|	|	|	|	|
140		140	|	|	|	|	|	|
141		|	|	|	|	|	|	|
|			|	|	|	|	|	|
142		|	|	|	|	|	|	|
143		143	143	143	|	|	|	|
|						|	|	|
144		144	144	144	|	|	|	|
145		|	|	|	|	|	|	|
|			|	|	|	|	|	|
146		|	|	|	|	|	|	|
147		147	|	|	|	|	|	|
|				|	|	|	|	|
148		148	|	|	|	|	|	|
149		|	|	|	|	|	|	|
|			|	|	|	|	|	|
150		|	|	|	|	|	|	|
151		151	151	|	|	|	|	|
|					|	|	|	|
152		152	152	|	|	|	|	|
153		|	|	|	|	|	|	|
|			|	|	|	|	|	|
154		|	|	|	|	|	|	|
155		155	|	|	|	|	|	|
|				|	|	|	|	|
156		156	|	|	|	|	|	|
157		|	|	|	|	|	|	|
|			|	|	|	|	|	|
158		|	|	|	|	|	|	|
159		159	159	159	159	|	|	|
|							|	|
160		160	160	160	160	|	|	|
161		|	|	|	|	|	|	|
|			|	|	|	|	|	|
162		|	|	|	|	|	|	|
163		163	|	|	|	|	|	|
|				|	|	|	|	|
164		164	|	|	|	|	|	|
165		|	|	|	|	|	|	|
|			|	|	|	|	|	|
166		|	|	|	|	|	|	|
167		167	167	|	|	|	|	|
|					|	|	|	|
168		168	168	|	|	|	|	|
169		|	|	|	|	|	|	|
|			|	|	|	|	|	|
170		|	|	|	|	|	|	|
171		171	|	|	|	|	|	|
|				|	|	|	|	|
172		172	|	|	|	|	|	|
173		|	|	|	|	|	|	|
|			|	|	|	|	|	|
174		|	|	|	|	|	|	|
175		175	175	175	|	|	|	|
|						|	|	|
176		176	176	176	|	|	|	|
177		|	|	|	|	|	|	|
|			|	|	|	|	|	|
178		|	|	|	|	|	|	|
179		179	|	|	|	|	|	|
|				|	|	|	|	|
180		180	|	|	|	|	|	|
181		|	|	|	|	|	|	|
|			|	|	|	|	|	|
182		|	|	|	|	|	|	|
183		183	183	|	|	|	|	|
|					|	|	|	|
184		184	184	|	|	|	|	|
185		|	|	|	|	|	|	|
|			|	|	|	|	|	|
186		|	|	|	|	|	|	|
187		187	|	|	|	|	|	|
|				|	|	|	|	|
188		188	|	|	|	|	|	|
189		|	|	|	|	|	|	|
|			|	|	|	|	|	|
190		|	|	|	|	|	|	|
191		191	191	191	191	191	|	|
|								|
192		192	192	192	192	192	|	|
193		|	|	|	|	|	|	|
|			|	|	|	|	|	|
194		|	|	|	|	|	|	|
195		195	|	|	|	|	|	|
|				|	|	|	|	|
196		196	|	|	|	|	|	|
197		|	|	|	|	|	|	|
|			|	|	|	|	|	|
198		|	|	|	|	|	|	|
199		199	199	|	|	|	|	|
|					|	|	|	|
200		200	200	|	|	|	|	|
201		|	|	|	|	|	|	|
|			|	|	|	|	|	|
202		|	|	|	|	|	|	|
203		203	|	|	|	|	|	|
|				|	|	|	|	|
204		204	|	|	|	|	|	|
205		|	|	|	|	|	|	|
|			|	|	|	|	|	|
206		|	|	|	|	|	|	|
207		207	207	207	|	|	|	|
|						|	|	|
208		208	208	208	|	|	|	|
209		|	|	|	|	|	|	|
|			|	|	|	|	|	|
210		|	|	|	|	|	|	|
211		211	|	|	|	|	|	|
|				|	|	|	|	|
212		212	|	|	|	|	|	|
213		|	|	|	|	|	|	|
|			|	|	|	|	|	|
214		|	|	|	|	|	|	|
215		215	215	|	|	|	|	|
|					|	|	|	|
216		216	216	|	|	|	|	|
217		|	|	|	|	|	|	|
|			|	|	|	|	|	|
218		|	|	|	|	|	|	|
219		219	|	|	|	|	|	|
|				|	|	|	|	|
220		220	|	|	|	|	|	|
221		|	|	|	|	|	|	|
|			|	|	|	|	|	|
222		|	|	|	|	|	|	|
223		223	223	223	223	|	|	|
|							|	|
224		224	224	224	224	|	|	|
225		|	|	|	|	|	|	|
|			|	|	|	|	|	|
226		|	|	|	|	|	|	|
227		227	|	|	|	|	|	|
|				|	|	|	|	|
228		228	|	|	|	|	|	|
229		|	|	|	|	|	|	|
|			|	|	|	|	|	|
230		|	|	|	|	|	|	|
231		231	231	|	|	|	|	|
|					|	|	|	|
232		232	232	|	|	|	|	|
233		|	|	|	|	|	|	|
|			|	|	|	|	|	|
234		|	|	|	|	|	|	|
235		235	|	|	|	|	|	|
|				|	|	|	|	|
236		236	|	|	|	|	|	|
237		|	|	|	|	|	|	|
|			|	|	|	|	|	|
238		|	|	|	|	|	|	|
239		239	239	239	|	|	|	|
|						|	|	|
240		240	240	240	|	|	|	|
241		|	|	|	|	|	|	|
|			|	|	|	|	|	|
242		|	|	|	|	|	|	|
243		243	|	|	|	|	|	|
|				|	|	|	|	|
244		244	|	|	|	|	|	|
245		|	|	|	|	|	|	|
|			|	|	|	|	|	|
246		|	|	|	|	|	|	|
247		247	247	|	|	|	|	|
|					|	|	|	|
248		248	248	|	|	|	|	|
249		|	|	|	|	|	|	|
|			|	|	|	|	|	|
250		|	|	|	|	|	|	|
251		251	|	|	|	|	|	|
|				|	|	|	|	|
252		252	|	|	|	|	|	|
253		|	|	|	|	|	|	|
|			|	|	|	|	|	|
254		|	|	|	|	|	|	|
255		255	255	255	255	255	255	255