Number patterns
Find the difference between two numbers next to each other, check it on the next pair, then use it.
Questions in this lesson
Transcript
In Primary 2, you completed number patterns by counting on and counting back. Today, we find the difference between the numbers in a pattern, and use it to find a missing number. Complete the number pattern. The numbers are three thousand, two hundred and fifty, three thousand, four hundred and fifty, three thousand, six hundred and fifty, and then a blank. Look at the first two numbers. Only the hundreds digit changes, from 2 to 4. Three thousand, four hundred and fifty minus three thousand, two hundred and fifty is two hundred. The second number is two hundred more. Next, the hundreds digit goes from 4 to 6. Three thousand, six hundred and fifty minus three thousand, four hundred and fifty is also two hundred. The next gap has the same difference. Each number is two hundred more than the number before it. We count on 2 hundreds, from 6 hundreds to 8 hundreds. Three thousand, six hundred and fifty plus two hundred is three thousand, eight hundred and fifty. The missing number is three thousand, eight hundred and fifty.
Complete the number pattern. The numbers are six thousand, eight hundred and forty, six thousand, five hundred and forty, six thousand, two hundred and forty, and then a blank. Try it first. Pause if you like. Look at the first two numbers. Only the hundreds digit changes, from 8 to 5. Six thousand, eight hundred and forty minus six thousand, five hundred and forty is three hundred. The second number is three hundred less. Next, the hundreds digit goes from 5 to 2. Six thousand, five hundred and forty minus six thousand, two hundred and forty is also three hundred. The next gap has the same difference. Each number is three hundred less than the number before it. We count back 3 hundreds, and we go past six thousand. Six thousand, two hundred and forty minus three hundred is five thousand, nine hundred and forty. The missing number is five thousand, nine hundred and forty.
Complete the number pattern. The numbers are two thousand, one hundred and eighty, two thousand, three hundred and eighty, then a blank, then two thousand, seven hundred and eighty. Try it first. Pause if you like. Look at the first two numbers. Only the hundreds digit changes, from 1 to 3. Two thousand, three hundred and eighty minus two thousand, one hundred and eighty is two hundred. The second number is two hundred more. Let us try two hundred more each time. We count on 2 hundreds, from 3 hundreds to 5 hundreds. Two thousand, three hundred and eighty plus two hundred is two thousand, five hundred and eighty. To check, count on 2 more hundreds, from 5 hundreds to 7 hundreds. Two thousand, five hundred and eighty plus two hundred is two thousand, seven hundred and eighty. So the missing number is right. The missing number is two thousand, five hundred and eighty. Find the difference between two numbers next to each other, check it on the next pair, then use it.