Question

Can you do these sums in your head?

(i) 38 + 63 + 37

(ii)

(iii) 375 + 1.75 + 3.25

(iv) 85 + 96 + 15

(v)

Answer 1

(i) 38 + 63 + 37

= 38 + (63 + 37)

= 38 + 100

= 138

(ii)

(iii) 375 + 1.75 + 3.25

= 375 + (1.75 + 3.25)

= 375 + 5

= 380

(iv) 85 + 96 + 15

= 85 + 15 + 96 (Using x + y = y + x)

= (85 + 15) + 96

= 100 + 96

= 96

(v)