Multiplication & division
Division Method
This is an efficient way to divide a 2-digit number by a 1-digit number. You estimate first, split the number into easy parts, then divide each part and add the results. Sometimes there is a remainder left over.
Estimate first
1. Find easy multiples of the divisor near your number. 2. For 75 / 4, use 40 / 4 = 10 and 80 / 4 = 20. 3. 75 is between 40 and 80, so the answer is between 10 and 20 (closer to 20).
Split, divide and add
1. Split the number into a friendly part and the rest, e.g. 75 = 40 + 35. 2. Divide each part: 40 / 4 = 10 and 35 / 4 = 8 remainder 3. 3. Add the whole parts: 10 + 8 = 18, and keep the remainder: 18 r3.
Round up or down for word problems
1. Work out the division and look at the remainder. 2. If you need enough of something (like packs), round UP. 3. If you are counting full groups (like full bags), round DOWN.
Worked examples
Estimating a quotient
- You want to work out 75 / 4.
- 40 / 4 = 10 and 80 / 4 = 20.
- 75 is between 40 and 80, and closer to 80.
Answer: The answer is between 10 and 20, closer to 20.
Dividing with a remainder
- Split 75 into 40 + 35.
- 40 / 4 = 10 (ten fours).
- 35 / 4 = 8 remainder 3 (eight fours, 3 left over).
- Add the whole parts: 10 + 8 = 18, remainder 3.
Answer: 75 / 4 = 18 r3.
Deciding to round up
- Parveen needs 28 balloons in packs of 5.
- 28 / 5 = 5 remainder 3.
- Five packs give only 25 balloons, which is not enough.
- So she must buy one more pack.
Answer: Parveen buys 6 packs.
Where you see this in real life
- Working out how many teams enter a competition when players divide into equal groups.
- Deciding how many packs to buy so you have enough for a party.
- Sharing money equally between a group of friends.
Key words
- Dividend
- The number being divided.
- Divisor
- The number you divide by.
- Quotient
- The answer to a division (how many whole groups).
- Remainder
- The amount left over that is smaller than the divisor.