Revise using expanded and compact addition to add

Revise using expanded and compact addition to add any pair of 3 -digit numbers. Today we are going to revise the expanded or compact layouts for adding 3 -digit numbers. 654 + 567 First let’s check using expanded addition. First, partition the numbers 100 1200 50+them +500 60 4 +++out 710 = =in 11=120 and 600 set columns, Put 1200 in theplace answer Put 201 in answer line and Put inthe answer line and according to their value. line, then recombine 100 line. 10 inthe thewaiting line. Leave a in space, then draw a line 1200, and 1. below. to write the 20 answer 600 50 4 + 500 60 7 100 10 1200 20 1 1200 + 20 + 1 = 1221 © hamilton-trust. org. uk 1 Year 3

Revise using expanded and compact addition to add any pair of 3 -digit numbers. Now let’s check with the compact method. 654 + 567 Without. Add partitioning, the Add the 10 s. 1 s. set out Add the 100 s. in columns. Put 2 the in the answer Putthe 1 innumbers answer line under Put 1 and 2 under the 1000 s Leave space, then ainline for under the 10 s 100 s the 1 s aand 1 in and 10 s 1 column in and 100 sthe in the answer line. answer. inthe thewaiting line. 654 + 567 11 1221 © hamilton-trust. org. uk 2 Year 3

Revise using expanded and compact addition to add any pair of 3 -digit numbers. The place value is exposed in the first which helps us to make sense of the numbers we are using, but the second takes up less space and is quicker to write. Let’s compare strategies. What do you like about each layout? 600 50 4 + 500 60 7 100 10 654 + 567 11 1200 20 1 1221 1200 + 20 + 1 = 1221 But importantly, both give us the correct answer! 3 © hamilton-trust. org. uk Year 3

Revise using expanded and compact addition to add any pair of 3 -digit numbers. Try these using your preferred strategy. 478 + 245 and 837 + 367 Let’s go through 837 + 367 using compact addition. Let’s go through 478 + 245 using expanded addition. 400 70 8 + 200 40 5 100 10 837 + 367 11 700 20 3 1204 700 + 20 + 3 = 723 © hamilton-trust. org. uk 4 Year 3