16 × 12 on the frame: one hundred, nine tens and two ones.
The big ideaBuild the ones part, keep the beads, then add the tens part.
How it works
Split the second number into tens and ones, so 12 is 10 and 2.
Build the ones part first and keep the beads on the frame.
Then add the tens part on top. Times ten moves every bead up one row.
The frame has three rows, so these sums stay below one thousand.
The plan for a two-digit sum.Ten rows of 16: every bead moves up one row, 160.
Example 1: 16 × 12, ten rows and two rows
Split 12 into 10 and 2.
Ten rows of 16: every bead moves up a row, so 10 × 16 = 160.
Two rows of 16: 2 × 16 = 32.
Join the parts: hundreds with hundreds, tens with tens, ones with ones.
160 + 32 = 192
16 × 12: 160 and 32 joined.
Example 2: 14 × 13, ones part first
Split 13 into 10 and 3.
Build the ones part first: 14 × 3 = 42. Keep the beads.
Add the tens part on top: 14 × 10 = 140.
42 + 140 = 182
14 × 13: 42 kept, then 140 added.
Example 3: 23 × 12, hundreds and tens
Split 12 into 10 and 2.
The ones part: 23 × 2 = 46. Keep the beads.
The tens part: 23 × 10 = 230.
46 + 230 = 276
23 × 12: two hundreds, seven tens and six ones.
Example 4: 21 × 14, an easy ones part
Split 14 into 10 and 4.
The ones part: 21 × 4 = 84.
The tens part: 21 × 10 = 210.
84 + 210 = 294
21 × 14: 84 and 210 together.
Words to know
split
Break a number into easy parts, like 12 into 10 and 2.
ones part
The part you build first, like 14 × 3.
tens part
The part you add on top, like ten rows of 14.
row of chairs
In the story, a line of the same number of chairs: twelve rows of sixteen.
Watch out
Keep the beads. Do not clear the frame between the two parts.
Add place by place: hundreds with hundreds, tens with tens, ones with ones.
Ten is just a move up a row, so splitting 13 into 10 and 3 is easier than splitting it into 6 and 7.
Mind the ones part. Two rows of fifteen make thirty, not twenty.
Try it
What is 12 × 11?
Which split of 13 is easiest to build?
What is 13 × 12?
What is 22 × 13?
Answers: 1. 132 · 2. 10 and 3 · 3. 156 · 4. 286
Try at homeAsk a grown-up to help you set out rows of cushions or books, like eleven rows of twelve. Count ten rows first, then the one row left, and add the two parts together.
For grown-upsSet out rows of cushions or books, like eleven rows of twelve. Count ten rows first, then the one row left, and join the two parts.
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