Using Number Properties

Problem: “Estimate 0.503 x 58.7.”

Discuss why ½ x 60 = 30 is sensible.

Problem: “Martha gets 34.56 ÷ 0.98 = 33.8688 on her calculator. Is she correct?”

(Answer: Martha must be wrong as division by a number less than 1 makes the  answer bigger.)

Problem: “Estimate 59.89 x 0.091.” (Possible answer: 59.89 x 0.091 ≈ 60 x 0.1, and 1 tenth of 60 = 6.)

Examples: Worksheet (Material Master 8–17).