Year 2: Totals and comparisons
Part of the Year 2 statistics chapter. Chapter overview · whole chapter on one page
Totals and comparisons
We can total the counts to find how many there are altogether.
We can compare two counts. We say how many more or how many fewer one has.
We can also put the counts in order, from fewest to most.
Always check your answer by counting again.
Key ideas
- To find how many altogether, add the counts together.
- To find how many more or fewer, take the smaller count from the bigger one.
- To sort the groups, compare their counts from the smallest to the biggest.
- Check each claim with the counts before you say Yes or No.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.ants 6, bees 3, frogs 5
- Add the counts together. Add them all, so none is missed.6 + 3 + 5 = 14
- Write the answer. 14
Check. Add them in the other order to check: 5 + 3 + 6 = 14. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Find each count. Then take the smaller count away from the bigger one.
- Count the ants. There are 6.ants: 6
- Count the bees. There are 3.bees: 3
- Take the smaller count away from the bigger one. The difference is how many more or fewer.6 - 3 = 3
- Write the answer. 3
Check. Add the difference back on: 3 + 3 = 6. ✓
Watch out. Take away the smaller number from the bigger one. Do not add them.
Method. Add the counts for each pair of rows. Find the pair that makes the total.
- List the pairs and their totals. Add the counts for each pair.ants 6 + bees 3 = 9; ants 6 + frogs 5 = 11; bees 3 + frogs 5 = 8
- Find the pair that makes 9. Only ants and bees make 9.9 = 9
- Write the answer. ants and bees
Check. ants and bees together make 9, and no other pair makes 9. ✓
Watch out. Check every pair. Two rows that are both bigger than the target cannot make it.
Watch out
Watch out: more or fewer? Take the smaller number from the bigger one, then read the question again.
Exam tip
Grown-up tip. Count two groups of beads or buttons and write both counts. Ask: “How many altogether? How many more is one than the other?”
Exercise 10F Totals and comparisons
Non-calculatorMethod. Count the shells once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2 3 4 5 6 7 8
- Read the last number. The last number is how many there are.8
- Write the answer. 8
Check. Count them again from the other end. You get 8 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Count the crabs once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2 3
- Read the last number. The last number is how many there are.3
- Write the answer. 3
Check. Count them again from the other end. You get 3 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Count the fish once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2 3 4 5
- Read the last number. The last number is how many there are.5
- Write the answer. 5
Check. Count them again from the other end. You get 5 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Count the octopuses once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2
- Read the last number. The last number is how many there are.2
- Write the answer. 2
Check. Count them again from the other end. You get 2 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.shells 8, crabs 3, fish 5, octopuses 2
- Add the counts together. Add them all, so none is missed.8 + 3 + 5 + 2 = 18
- Write the answer. 18
Check. Add them in the other order to check: 2 + 5 + 3 + 8 = 18. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Find each count. Then take the smaller count away from the bigger one.
- Count the shells. There are 8.shells: 8
- Count the crabs. There are 3.crabs: 3
- Take the smaller count away from the bigger one. The difference is how many more or fewer.8 - 3 = 5
- Write the answer. 5
Check. Add the difference back on: 3 + 5 = 8. ✓
Watch out. Take away the smaller number from the bigger one. Do not add them.
Method. Find each count. Then take the smaller count away from the bigger one.
- Count the shells. There are 8.shells: 8
- Count the fish. There are 5.fish: 5
- Take the smaller count away from the bigger one. The difference is how many more or fewer.8 - 5 = 3
- Write the answer. 3
Check. Add the difference back on: 5 + 3 = 8. ✓
Watch out. Take away the smaller number from the bigger one. Do not add them.
Method. Compare the counts. The biggest count is the most.
- Write down each count. Put each count next to its name.shells 8, crabs 3, fish 5, octopuses 2
- Find the biggest count. 8 is the biggest count.biggest: 8
- Write the answer. The shells row has 8.shells
Check. Every other count is smaller than 8. ✓
Watch out. Check every count, not only the first two. The most is the count that is bigger than all the others.
Method. Find each count, then put the rows in order of their counts, fewest first.
- Write down each count. Put each count next to its name.shells 8, crabs 3, fish 5, octopuses 2
- Put the counts in order, fewest first. Start from the smallest count.2 → 3 → 5 → 8
- Write the order. octopuses, crabs, fish, shells
Check. Check that each count is bigger than the one before it. ✓
Watch out. Compare the counts, not the names. The longest name does not mean the biggest count.
Method. Add the counts for each pair of rows. Find the pair that makes the total.
- List the pairs and their totals. Add the counts for each pair.shells 8 + crabs 3 = 11; shells 8 + fish 5 = 13; shells 8 + octopuses 2 = 10; crabs 3 + fish 5 = 8; crabs 3 + octopuses 2 = 5; fish 5 + octopuses 2 = 7
- Find the pair that makes 10. Only shells and octopuses make 10.10 = 10
- Write the answer. shells and octopuses
Check. shells and octopuses together make 10, and no other pair makes 10. ✓
Watch out. Check every pair. Two rows that are both bigger than the target cannot make it.
Method. Add up each side of the claim, then compare the two totals.
- Add the counts for fish. They make 5 altogether.5 = 5
- Add the counts for crabs and octopuses. They make 5 altogether.3 + 2 = 5
- Compare the two totals. 5 is the same as 5.No
Check. The claim compares fish with crabs and octopuses. It is not right. ✓
Watch out. Add the counts on each side first. Then compare the totals, not the single rows.