Maths Board for this week

Welcome back to my blog!,

This weeks question for my maths board was 159+57, first thing I thought when i saw I 159 was rounding it up to 160, so thats what did, I also did it to the 57, so my two new numbers were 160 and 60, I added 40 onto the 160 which would be 200 and then add on 20 because I know that there is  20 left because 40+20 is 60. now that i had added the 20 on I had 220, but I still have to take away the extra numbers from when I rounded up which are 1 and 3 which together is 4 so I too away 4 from 220 which gives my  answer 216.

If you would like to see my actual maths board here it is

How would you work this out?