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Ages 5+ · Abacus · Adding
Adding past ten
tensones13
13 on the frame: one ten on top and three ones below.
The big ideaTen ones trade for one ten. The rest stay as ones.

How it works

A row holds only ten beads. When the ones row is full, trade it.

Ten ones trade for one ten on the row above.

The beads that are left over stay on the ones row.

Nine and two make eleven: one ten and one one.

tensones
Before the trade: eight ones are across.
tensones13
After 8 + 5: one ten and three ones.

Example 1: 9 + 2

  1. Nine ones are across.
  2. One more bead fills the row: that is ten ones.
  3. Trade the ten ones for one ten on the top row.
  4. One more bead is left, so slide it across on the ones row.
  5. 9 + 2 = 11, which is one ten and one one.
tensones11
9 + 2 = 11

Example 2: 8 + 5

  1. Eight ones are across.
  2. Two more fill the row: 8 + 2 = 10.
  3. Trade the ten ones for one ten.
  4. Three beads are left over: 5 − 2 = 3.
  5. 8 + 5 = 13, which is one ten and three ones.
tensones13
8 + 5 = 13

Example 3: 9 + 6

  1. Nine ones are across.
  2. One more fills the row: 9 + 1 = 10.
  3. Trade ten ones for one ten.
  4. Five beads are left over: 6 − 1 = 5.
  5. 9 + 6 = 15
tensones15
9 + 6 = 15

Example 4: A tray of ten

  1. A tray has ten holes. Ben has thirteen beads.
  2. Ten beads fill one tray.
  3. Three beads are left over for a new tray.
  4. 10 + 3 = 13
tensones
One full ten and three ones.

Words to know

trade
Ten ones become one ten on the row above.
a ten
A full row of ten beads.
tray
A tray holds ten beads, like a full row.

Watch out

Try it

  1. What is 9 + 2?
  2. What is 8 + 5?
  3. What is 9 + 6?
  4. Ten ones trade for how many tens?
Answers: 1. 11 · 2. 13 · 3. 15 · 4. One ten
Try at homeAsk a grown-up to help you line up ten small things, like blocks, in a row. That is a ten. Now add three more and count them all: one ten and three ones.
For grown-upsLine up ten small things, such as blocks, in a row: that is a ten. Add three more and count them all: one ten and three ones.
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