Tens, Ones and Hundreds

Counting to a Hundred #

Ten rows of ten, counted either way.

Counting in tens reaches a hundred in ten steps instead of a hundred

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One full row is ten squares. Count along it in ones: 1, 2, 3, all the way to 10.

Every new row adds another ten. Three full rows: 10, 20, 30.

Counting in tens is quicker: 10, 20, 30, 40, 50, 60, 70 — seven rows, seven words.

Ten rows of ten fill the square. Ten tens is one hundred.

Skip Counting #

Same-size jumps, from twos up to thousands.

Skip counting jumps by the same amount every time

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Counting in twos rings every second number: 2, 4, 6, 8 — one jump of two each time.

Counting in fives, every number ends in 5 or 0 — the rings make two columns.

Counting in tens, every number ends in 0: 10, 20, 30, 40, 50 — one column.

Bigger jumps work the same: 100, 200, 300 — one hundred at a time.

Odd and Even Numbers #

Pairs up cleanly, or one is left over.

An even number pairs up with none left over; an odd number leaves one

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Six pairs up perfectly: three twos and nobody left over. Six is even.

Seven tries the same and one is left standing alone. Seven is odd.

The evens end in 0, 2, 4, 6 or 8 — count in twos and you land on every one.

Tens and Ones #

A two-digit number is tens and ones.

A two-digit number is a count of tens and a count of ones

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23 is 2 groups of ten and 3 ones.

The digit on the left counts the groups of ten.

The digit on the right counts the ones that did not fill a group.

Ten ones fill a group, so ten ones become one ten: that is why 10 is written with a 1 and a 0.

Number Words to a Thousand #

The hundreds first, then tens, then ones.

Number words follow the tens and ones: forty-seven is forty and seven

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Every tens number has its own word: twenty, thirty, forty, fifty — up to ninety.

Forty-seven says its tens first, then its ones: forty and seven.

The teens say their ones first: thirteen is three-and-ten, one ten underneath.

Past a hundred the pattern holds: three hundred forty-five, biggest place first.

Hundreds #

Ten tens pushed together make a hundred.

Ten groups of ten push together into one square of a hundred

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Here are 9 groups of ten. Add 1 more group and watch what happens.

The 10 groups join into one square of a hundred. Ten tens make 100.

Any 3-digit number is made of hundreds, tens and ones.

Ordering Numbers #

More digits wins; then the leftmost difference.

More digits wins; when digits match, the leftmost different digit decides

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87 or 132? The 3-digit number is further along — more digits always wins.

Same number of digits: compare from the left, place by place, until one differs.

Ordered smallest to largest, they sit left to right: 87, 340, 390.