The part adder - Make your own hard sums

In this photo I used the rounding strategy by adding 2 onto 48 and 1 onto 49 to make it 50 + 50 then - 2 and 1 to end up with 97.

In this photo I used the Spliting strategy by taking away 7 from 48 and added 41 and 49 to make 90 then I added 7 to end up with 97. 

In this photo I use the rounding strategy by adding 1 to 49 to make 50 then + the 48 and the 50 to make 98 then I toke away 1 to make 97.

Sylis and Oh Hsen helped me to find 3 different ways to solve 48 + 49 on the Part adder - Make your own hard sums.