Unit 8: Numbers to 100 (2) Question 14

Arun says: "21 is 2 tens and 1 one. $2 + 1 = 3$ so there will only be 3 ways to regroup 21 using tens and ones."

Is Arun correct? If he is correct, will Arun's method always tell you how many different ways there are to regroup a number?

Discuss with a partner.