Multiplication
What is the greatest two-digit number you can multiply by 10 to get a result just under 1,000? Explain your answer.
99. 99×10=990. 99 is the largest two-digit number, and multiplying by 10 moves digits left once, making 990.
920 tickets are sorted into packs of 10 tickets each. How many packs are there?
920÷10=92. Each digit moves right once.
Write and solve 21×102 . Explain.
21×102=2,100. 102=100 102=100; multiplying by 100 moves digits two places left.
There are 8 telescopes, each used by 10 astronomy teams. Total teams?
Answer: 80. 8×10=80.
12 trombones with 7 slides each: how many slides in all?
Answer: 84. 12×7=84
A class has 29 books in each shelf, and there are 10 shelves. Then, if the librarian adds one more book to each shelf, how many books are on all the shelves now?
29×10=290 is the original. Adding 1 to each shelf: 10×1=10, so total is 290+10=300
A sports club has 4,800 cones, shared equally among 100 teams. How many cones per team?
4,800÷100=48. Each digit moves right twice.
Calculate 32×103 using powers and place value.
102=100, so 7,200÷100
A moon orbits its planet every 365 days. What’s the total days for 10 orbits?
Answer: 3,650. 365×10=3,650.
There are 18 flute players, each with 10 music stands. Total stands?
Answer: 180. 18×10=180
There are 76 tables in a school hall and each table seats 100 children. What is the total number of children seated?
7,600. 76×100=7,600. Each digit moves two places left in place value.
You have 56,000 marbles to split into groups of 1,000. How many groups will there be? Explain.
56. 56,000÷1,000=56; three digits move right.
What is 7,200÷102? Show your reasoning.
Answer: 72. 102=100, so 7,200÷100=72. Move the digits two places to the right.
A Mars rover collects exactly 24 soil samples every day for 100 days. How many samples?
Answer: 2,400. 24×100=2,400
Each day, a shop sells 15 clarinets and is open for 100 days. How many clarinets sold?
Answer: 1,500. 15×100=1,500
The caretaker buys 234 boxes of tissue, each box has 1,000 tissues. How many tissues in total?
Answer: 234,000. 234×1,000=234,000. Each digit moves three places to the left in place value.
If 13,600 pencils are distributed evenly into boxes of 100, how many boxes are used?
13,600÷100=136.
A shop sells 45×102 pens per week. How many pens would they sell in 10 weeks?
Answer: First, 45×102=4,500 per week; so 4,500×10=45,000 pens in 10 weeks.
If a comet appears every 75 years, how many years for it to show up 1,000 times?
Answer: 75,000. 75×1,000=75,000.
A group of 1,800 trumpets is packed into boxes of 100. How many boxes?
Answer: 18. 1,800÷100=18
500 points: You know that n×100=6,400. What is n? Then, what is n×1,000?
n=64 because 64×100=6,400; 64×1,000=64,000
A teacher wants to divide a large class of 96 students into equal groups. The size of each group must be a factor of both 96 and 24, greater than 1 but smaller than 20. How many possible group sizes can the teacher choose, and what are they?
There are 5 possible group sizes: 2, 3, 4, 6, and 12.
Find the answer to 81,000÷103 and explain the steps.
Answer: 81. 103=1,000 81,000÷1,000=81 moving three digits right.
There are 3,100 meteorites and they are sorted into 100 crates. How many meteorites per crate?
Answer: 31. 3,100÷100=31
If 23 musicians play 1,000 notes each in a festival, how many notes played overall?
Answer: 23,000. 23×1,000=23,000