Year 2: Making an amount with coins

Method. Add the amounts together. Start with the biggest one, then count on.

1. Start with 10p. Start with the biggest amount. Then count on.
   10p
2. Add 5p. Add the next amount to the total so far.
   10p + 5p = 15p
3. Write the answer.
   15p

Check. Add them in a different order: 5p + 10p = 15p. ✓

Watch out. Add the amounts in the same unit. Pence with pence, pounds with pounds.

Method. Add the amounts together. Start with the biggest one, then count on.

1. Start with 20p. Start with the biggest amount. Then count on.
   20p
2. Add 2p. Add the next amount to the total so far.
   20p + 2p = 22p
3. Add 1p. Add the next amount to the total so far.
   22p + 1p = 23p
4. Write the answer.
   23p

Check. Add them in a different order: 1p + 2p + 20p = 23p. ✓

Watch out. Add the amounts in the same unit. Pence with pence, pounds with pounds.

Method. Add the amounts together. Start with the biggest one, then count on.

1. Start with 50p. Start with the biggest amount. Then count on.
   50p
2. Add 20p. Add the next amount to the total so far.
   50p + 20p = 70p
3. Add 20p. Add the next amount to the total so far.
   70p + 20p = 90p
4. Write the answer.
   90p

Check. Add them in a different order: 20p + 20p + 50p = 90p. ✓

Watch out. Add the amounts in the same unit. Pence with pence, pounds with pounds.

Method. Find two coins that add up to the amount. Try the bigger coins first.

1. Try two coins. Pick two coins and add their values.
   20p + 5p
2. Add them up. The total must be the amount we want.
   20p + 5p = 25p
3. Write the answer. No other two coins make this amount.
   20p and 5p

Check. Add them the other way round: 5p + 20p = 25p. ✓

Watch out. The two coins can be the same, like two 50p coins.

Method. Start with the coin we know. Count on to the total to find the other coin.

1. Start with 2p. This is the coin we know.
   2p
2. Count on to 7p. The amount we count on is the other coin.
   2p + ? = 7p
3. Write the other coin.
   5p

Check. Add the two coins: 2p + 5p = 7p. ✓

Watch out. Check that the two coins make the total, not just one of them.

Method. Add the amounts together. Start with the biggest one, then count on.

1. Start with 200p. Start with the biggest amount. Then count on.
   200p
2. Add 50p. Add the next amount to the total so far.
   200p + 50p = 250p
3. Change pence to pounds. 100p is the same as £1.
   250p = £2.50
4. Write the answer.
   £2.50

Check. Add them in a different order: 50p + 200p = 250p. ✓

Watch out. Add the amounts in the same unit. Pence with pence, pounds with pounds.

Method. Add up each set. The set that makes 40p is the right one.

1. Add up set A. Add the value of each coin.
   20p + 10p + 10p = 40p
2. Add up set B. Add the value of each coin.
   20p + 20p + 5p = 45p
3. Add up set C. Add the value of each coin.
   50p + 5p = 55p
4. Write the answer. Only one set makes 40p.
   A

Check. The other sets do not make 40p, so only set A is right. ✓

Watch out. Add every coin in the set. Do not stop after the first two coins.

Method. Use the biggest coin you can first. Then make the rest with as few coins as you can.

1. Start with the biggest coin that fits. A bigger coin means fewer coins.
   20p
2. Add the coins, one at a time. Keep adding the biggest coin that fits.
   20p + 20p = 40p
3. Count the coins. That is 2 coins altogether.
   2 coins
4. Write the answer. No other way uses fewer coins.
   2

Check. Add the coins again: 20p + 20p = 40p. ✓

Watch out. Use the biggest coins first. This gives the fewest coins.

Method. Add one coin at a time until you reach 25p.

1. Add one coin at a time. Each coin is worth 5p.
   5p, 10p, 15p, 20p, 25p
2. Count how many coins you added. The number of coins is the number of steps.
   5 coins
3. Write the answer.
   5

Check. Check: 5 × 5p = 25p. ✓

Watch out. Add the same coin each time. Do not add 1 each time.

Method. List what three 10p coins can make, then check 25p is in the list.

1. Add the coins. Each coin is 10p, so the totals go up in tens.
   10p, 20p or 30p
2. Is 25p in the list? No total with 10p coins ends in 5.
   25p is not in the list
3. Decide. Mo cannot make 25p with three 10p coins.
   No

Check. Check the totals: 10 + 10 = 20 and 10 + 10 + 10 = 30. ✓

Watch out. Coins of one value can only make amounts that are multiples of that value.

Method. Find how much more we need. Take what we have away from the amount we want.

1. Find the amount we want. This is the total we need.
   50p
2. Find the amount we have. These are the coins we already have.
   30p
3. Take away what we have. The difference is how much more we need.
   50p − 30p = 20p
4. Write the answer.
   20p

Check. Add it back: 30p + 20p = 50p. ✓

Watch out. Take away the amount we have, not the amount we want.