Grade 5 Mental Math Problems

#1. When asked to multiply 26 x 11, Kate thinks 260 + 26. Explain Kate's thinking.

#2. Solve 25 x 16 two different ways and show your thinking.

#3. When asked to multiply 39 x 7, Glen said he knew that 40 x 7 was 280. What does Glen have to do next? Why?

#4. Cathy is buying a birthday card for $2.99 and a get well card for $2.97. Determine the total cost.

#5. When asked to multiply 723 x 5, Steven said he'd start with 3500. What is doing to find the product? What does he need to do next?

#6. Danny saved $500 over the winter shoveling driveways. When spring arrived he bought a new mountain bike for $299. How much money does Danny have left?

#7. When Sue saw the question 4 x 12 x 25 she immediately knew the answer was 1200. How did

Sue arrive at the product so quickly?

#8. When 4_2 is divided by 8 the quotient is about 60. What is the value of the missing digit?

#9. When asked to provide an estimate for the product of 77 x 32, Kelly said "about 2400". How did Kelly arrive at this value?

#10. Marcus was at the sporting goods store and was pricing items to take on his camping trip. The Coleman stove was $135, a new fishing rod was $55, a sleeping bag was $65, and a cooler was $45. What strategy could Marcus use to quickly determine the total cost?