Question

Miranda needs to add 68 + 19 mentally but is struggling. If she knows that 68 + 20 = 88, how can she use this to help?

Answer 1

She can use 68 + 20 = 88 to help by noticing that the 20 is ahead of 19 by 1. She can easily mentally turn the 20 into a 19 and realized that the 88 would become 87.