Commutative number sentences II

This task is about completing number sentences.

Question 1Change answer

a) For each problem, find the missing number and write it in the box.
 
   i)   35 + 28 = 28 + 
   ii)  148 +  = 97 + 148
   iii)  + 496 = 496 + 375
   iv)  919 + 762 =  + 919

Question 1Change answer

b) All the number sentences below are true. Explain why you know they are true without having to add up the numbers.
 

638 + 95 = 95 + 638

277 + 534 = 534 + 277

1 632 + 817 = 817 + 1 632

28 357 + 4 216 = 4 216 + 28 357