As part of unit A3 the children have been finding the difference between numbers by adding.
Method
26 + ___ = 78
Method 1
26+2 =28
28+50=78
50+2= 52
So, 26+52=78
Method 2
Number line with 26 at the beginning and 78 at the end. Count on from 26 to 28 = 2 jumps. Then count in tens to 78= 50+2=52.
Method 3
Number line with 26 at the beginning and 78 at the end. Count on from 26 to 30= 4. Then add 40 to get to 70. Finally add 8 to get tp