Page 35 - Math Smart - 7

Divisibility test Square numbers
A divisibility test is a quick way of finding out A square number is the product obtained when
whether a given integer is divisible by a divisor a whole number is multiplied by itself.
without doing the division calculation.
Square Numbers
Number Test for divisibility
1^=1 1l2= 121
2 All even numbers are divisible by
2^ = 4 122= 144
2. A number is divisible by 2 if the
last digit is 0, 2, 4, 6 or 8. 32 = 9 132 = 169
3 A number is divisible by 3 if the 42 = 16 II 142 = 196
sum of its digits is divisible by 3. 52 = 25 1 152 = 225
4 A number is divisible by 4 if the 62 = 36 162 = 256
number formed by its last two II MC
II
72 = 49 172 = 289
II
digits is divisible by 4.
182 = 324
5 A number is divisible by 5 if its
00
last digit is 0 or 5. 92 = 81 192 = 361
II
»st.
6 A number is divisible by 6 if it is 102= 100 202 ^ 400
divisible by 2 and also divisible by
3. You must use both tests. Square roots
8 A number is divisible by 8 if the The square root of a certain number is a value
number formed by its last three that can be multiplied by itself to give that
digits is divisible by 8. certain number.

9 A number is divisible by 9 if the
Square roots
sum of its digits is divisible by 9.
10 A number Is divisible by 10 if its ^/f=1 V121 =11 V256 = 16
last digit is 0.
V49 = 7 V144 = 12 V289 = 17
100 A number is divisible by 100 if its
last two digits are 00.
^^ = 3 V^ = 8 Vl69 = 13 V324 = 18

9
V^ = Vl96 = 14 V361 =19
VToo = loi V225 = 15 V400 = 20