Estimation for Multiplication
Lucille claims that a good estimate for 43 x 17 would be about 60. Do you agree or disagree and why?
Find the product: 24 x 16
384
Find the quotient: 1505 and 7
215
JJ solved 1564 divided by 4 and got a quotient of 391. Justify JJ's math by using the inverse operation. Was he correct or incorrect?
391 x 4 = 1564. JJ was CORRECT!
Ian bought 1,776.25 grams of baking soda for an experiment. He needed to split the total equally into 35 bags. How many grams of baking soda are in each bag?
1776.25 divided by 35 = 50.75 grams in each bag
Patty claims that a good estimate for 51 x 12 would be about 50. Do you agree or disagree and why?
Disagree because 51 is close to 50 and 12 is close to 10. 50 x 10 is 500, not 50. They forgot to add a zero.
Find the product: 35 and 18
630
Find the quotient: 3978 and 9
442
John solved 3090 divided by 15 and got a quotient of 205. Justify John's math by using the inverse operation. Was he correct or incorrect?
205 x 15 = 3075. John was INCORRECT. He should have gotten a quotient of 206.
Phillip bought some ingredients to make cookies. He bought 7.8 pounds of flour for $1.50 per pound. He also bought 2.75 pounds of sugar for $3.60 per pound.
A) How much did Phillip spend on flour?
B) How much did he spend of sugar?
$1.50 x 7.8 = $11.70 on flour
$3.60 x 2.75 = $9.90 on sugar
Choose all reasonable estimations for 14.07 x 6.3:
a. 84
b. 140
c. 60
d. 30
A & C
Find the product: 14.06 x 7.2
101.232
Find the quotient: 178.75 and 13
13.75
Sarah solved 355 divided by 25 and got a quotient of 142. Justify Sarah's math by using the inverse operation. Was she correct or incorrect?
14.2 x 25 = 355. Sarah was INCORRECT! She forgot to put the decimal point in her answer. Her quotient should have been 14.2.
Mr. Carl ordered 396 marbles for a game with his class. He wanted to give his 24 students an equal amount of marbles. How many marbles will each student get?
2064 divided by 24 = 16.5 marbles. You can't give each student half a marble, so they would each get 16 whole marbles.
Choose all reasonable estimations for 16.09 x 8.4:
a. 136
b. 128
c. 20
d. 200
B & D
Find the product: 20.13 and 4.8
96.624
Find the quotient: 849.6 and 36
23.6
Cleo solved 528 divided by 32 and got a quotient of 16.5. Justify Cleo's math by using the inverse operation. Was she correct or incorrect?
16.5 x 32 = 528. Cleo was CORRECT.
Fiona went to the store to buy some veggies. She bought 2.3 ounces of carrots that cost $3.50 per ounce. She also bought 4.25 ounces of peppers that cost $1.20 per ounce. She paid with a $20 bill.
A) What was the total cost of her purchase?
B) How much change did she get back?
$2.30 x 3.5 = $8.05 (cost of carrots)
$1.20 x 4.25 = $5.10 (cost of peppers)
$8.05 + $5.10 = $13.15 (total cost)
$20 - $13.15 = $6.85 (change)