Question

Find the smallest square number that is divisible by each of the numbers 4,9,20

Answer 1

1.   What will be the unit digit of the squares of the following numbers?

        (i) 81

(ii) 272

(iii) 799

(iv) 3853

        (v) 1234

(vi) 26387

(vii) 52698

(viii) 99880

        (ix) 12796

(x) 55555

Sol: (i) ∵ 1 × 1 = I

              ∴ The unit’s digit of (81)2 will be 1.

         (ii) 2 × 2 = 4

              The unit’s digits of (272)2 will be 4.

         (iii) Since, 9 × 9 = 81

              The unit’s digit of (799)2 will be 1.

         (iv) Since, 3 × 3 = 9

              The unit’s digit of (3853)2 will be 9.

         (v) Since, 4 × 4 = 16

              The unit’s digit of (1234)2 will be 6.

         (vi) Since 7 × 7 = 49

              The unit’s digit of (26387)2 will be 9.

         (v) Since, 8 × 8 = 64

              The unit’s digit of (52698)2 will be 4.

         (vi) Since 0 × 0 = 0

              The unit’s digit of (99880)2 will be O.

         (vii) Since 6 × 6 = 36

              The unit’s digit of (12796)2 will be 6.

         (x) Since, 5 × 5 = 25

              The unit’s digit of (55555)2 will be 5.

Answer 2

8,15and20 is the smallest number