Powers of 10 & Mental Math
What is 45 x 10?
450
12x12
144
213x3
639
Maya buys $6 boxes of colored pencils. Each box contains $24 pencils. How many pencils does Maya have in total?
144 pencils
Estimate the product of 49 x 11 by rounding both numbers to the nearest ten.
50x10=500
what is 32x100?
3,200
15x14
210
402x4
1,608
A Grade 5 classroom has 5 rows of desks with 6 desks in each row. If there are 4 identical Grade 5 classrooms in the school, how many total desks are there?
120
Without calculating the exact answer, is 38x 22 greater than or less than 1,000? Explain.
less than
What is 60x40?
2,400
24x15
360
125x6
750
An apple orchard in Ontario harvested 18 crates of apples. If each crate holds 35 apples, how many apples were harvested altogether?
630
A student calculated 62x39 = 24,180. Explain why this answer is unreasonable without working out the full calculation.
The estimate should be 60x40 = 2,400. The student's answer is ten times too large (about 24,000 instead of $2,400).
140
35x24
840
350x5
1,750
Liam saves $45 every month for $2 full years (24 months). How much money has Liam saved in total?
1,080
If you estimate 28x43 as 30x40 = 1,200. did you overestimate or underestimate factor 28? Is 1,200 a close estimate?
28 was overestimated (rounded up to 30). Yes, it's very close! (The actual answer is 1,204)
what is 700x80?
56,000
48x53
2,544
624x8
4,992
A school concert sold 32 student tickets for $8 each and $25 adult tickets for $12 each. How much money was raised from ticket sales in total?
556
A park is 45 metres long and 20 metres wide. What is its total area?
900 metres squared