Hundreds, tens, ones and patterns

Ten tens make one hundred

Count bundles of ten: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100. You can exchange ten tens for one hundred without changing the amount.

Count hundreds: 100, 200, 300, 400. Count back in hundreds from 300: 200, 100, 0. Four hundreds, two tens and seven ones make 427, four hundred and twenty-seven.

The zero in 407 holds the tens place. It means there are no tens between the four hundreds and seven ones. Leaving it out gives 47, a different amount. Ten hundreds make 1000, one thousand.

Read and write the same amount

To write six hundred and three, record six hundreds, no tens and three ones: 603. Writing 63 would leave out the empty tens place and change the amount.

To write 630 in words, read its nonempty places: six hundreds and three tens. That is six hundred and thirty. The zero is still needed in the numeral, but there is no ones part to name in the words.

Twelve tens make one hundred and two tens. Three hundreds, twelve tens and six ones therefore make 426, not 3126. Join equal amounts before writing one digit in each place. At the upper boundary, ten hundreds make 1000.

Compare the first place that differs

Compare 368 and 402. Four hundreds is greater than three hundreds, so 402 is greater.

Compare 368 and 386. The hundreds match. Eight tens is greater than six tens, so 386 is greater. You do not need to compare the ones after a larger place has decided the order.

Check your understanding 1 Order close numbers

Put 509, 590 and 599 in increasing order. Write the smallest in words.

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509, 590, 599. All have five hundreds. Zero tens comes before nine tens; then compare zero ones with nine ones. The smallest is five hundred and nine.

Follow the pattern across a hundred

In 365, 375, 385, 395, 405, each step adds ten. At 395, adding another ten makes ten tens. Exchange those for a hundred: 395 + 10 = 405. The ones stay five.

For 620, 520, 420, 320, each step takes away one hundred. The next number is 220.

Check your understanding 2 Use the same jump

The same step is used each time: 780, 790, 800. Choose add or subtract, give the step size, then write the next two numbers.

Add or subtract?

SubtractCorrectIncorrectAddCorrectIncorrect

Step size

First next number

Second next number

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Add ten each time. The next two numbers are 810, 820. The same step must work between every neighbouring pair, including across 800.

Pair to find odd and even

Put counters in pairs. An even number leaves no counter without a partner. An odd number leaves one.

Every ten is even, so hundreds and tens can already be paired. The ones digit decides: 0, 2, 4, 6 and 8 give even numbers; 1, 3, 5, 7 and 9 give odd numbers.

Eight counters make four pairs with none left over, so 8 is even. Nine counters make four pairs with one left over, so 9 is odd. Zero counters leave none without a partner: 0 is even.

Check your understanding 3 Look at the ones place

205 has an even hundreds digit. Does that make the whole number even?

Is 205 odd or even?

EvenCorrectIncorrectOddCorrectIncorrect

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205 is odd. Hundreds and tens can already be paired. The five ones leave one counter without a partner, so the ones digit decides. The number 1000 is even: ten hundreds leave none without a partner.

Try without the table

Write six hundred and three. Write 630 in words. Are both numbers odd, both even, or one of each?

Your numeral, number words and odd/even decisions, or work on paper