Today in Maths we were using compatible numbers to add a series of two digit numbers. Compatible numbers are ones that add to a tidy sum (10, 100): like 8 and 2, 7 and 3, 6 and 4, 1 and 9 and 5 and 5. We were given a series of numbers to add, and then had to find the ones digits that added to 10. For example:
24 + 36 + 12 + 38 + 15 = So, (4 and 6), (2 and 8) + 5 = 25
Then we added the tens digits, by rearranging them into groups,
So, 3 tens and 3 tens + 1 ten + 1 ten + 2 ten = 10 tens
Then we added our tens and ones together.
So, 10 tens (100) + 25 ones = 125. Here are photos of us solving these tricky addition problems using compatible numbers.
