Shapes are numbers in disguise.
Can you crack every secret?
One puzzle at a time. Tap Start when you're ready.
First — the big rule
A shape is a number in disguise. In one puzzle, the same shape always hides the same number.
♥ + ♥ = 10
Both hearts are the same number. Which number, added to itself, makes 10?
♥ = 5
Because 5 + 5 = 10. Always check by putting the number back in!
Find the hidden number
▲ + ▲ = 14
▲ =
Find the hidden number
■ + ■ + ■ = 18
■ =
Find the hidden number
● + ● + ● + ● = 20
● =
Find the hidden number
★ + ★ = 26
★ =
Find the hidden number
◆ + ◆ + ◆ = 36
◆ =
Next — a shape and a number
Now the shape hides next to a number you can see. Ask yourself: what number would make this true?
▲ + 4 = 11
▲ = 7
Because 7 + 4 = 11. Count on from 4 if you need to: 5, 6, 7... or think 11 − 4.
A shape and a number
▲ + 6 = 15
▲ =
A shape and a number
■ − 4 = 11
■ =
A shape and a number
9 + ● = 23
● =
A shape and a number
★ − 17 = 25
★ =
A shape and a number
◆ + 28 = 65
◆ =
A shape and a number
54 − ♥ = 19
♥ =
Next — two shapes together
Two different shapes hide two different numbers. One secret is given to you — use it to crack the other one.
▲ + ■ = 13 and ▲ = 5
The triangle is 5, so the puzzle becomes 5 + ■ = 13.
■ = 8
Check: 5 + 8 = 13. It works!
Two shapes together
▲ + ■ = 19
▲ = 9, so ■ =
Two shapes together
● + ★ = 31
★ = 16, so ● =
Two shapes together
◆ + ♥ = 48
◆ = 27, so ♥ =
Two shapes together
▲ − ■ = 6
▲ = 20, so ■ =
Two shapes together
■ + ■ + ▲ = 30
▲ = 8, so ■ =
Challenge puzzle
Nobody tells you either number this time!
▲ + ■ = 24
▲ + ▲ + ■ = 37
Hint: the second line has everything the first line has — plus one extra ▲. How much bigger is 37 than 24?
▲ = ■ =
Now YOU write in shapes
Here is a secret key. Each number has its own shape:
3 = ◆ 4 = ▲ 7 = ■ 9 = ★ 11 = ● 12 = ♥
So the number equation 4 + 7 = 11 becomes...
▲ + ■ = ●
Swap every number for its shape. The + and = stay the same.
Write it in shapes
3 = ◆ 4 = ▲ 7 = ■ 9 = ★ 11 = ● 12 = ♥
12 − 3 = 9
− =
Tap a box, then tap its shape.
Write it in shapes
3 = ◆ 4 = ▲ 7 = ■ 9 = ★ 11 = ● 12 = ♥
4 + 3 = 7
+ =
Tap a box, then tap its shape.
Write it in shapes
3 = ◆ 4 = ▲ 7 = ■ 9 = ★ 11 = ● 12 = ♥
9 + 3 = 12
+ =
Tap a box, then tap its shape.
Number machines
Grown-ups call these function machines. A machine takes a number in, does the same thing to it every time, and sends a new number out.
This machine adds 2. The rule is written on it — nothing to guess. Tap the machine to feed it a number.
Tap the machine!
Your turn — the +2 machine
Same machine, same rule. Say it out loud: “in... add 2... out.”
● ○ ○ ○
The machine keeps a list
When a machine does lots of numbers, we write them in a list called a table. This is the same +2 machine — just as a list. The first row is done for you.
| IN | OUT |
|---|---|
| 3 | 5 |
| 5 | |
| 10 | |
| 14 |
One new machine — it takes away 3
Now the same machine, as a list. Fill in what comes out, one row at a time.
| IN | OUT |
|---|---|
| 9 | |
| 12 | |
| 15 | |
| 7 |
Guess the rule
This machine hides its rule — but it still does the same thing every time. Tap to run it, and watch.
What does the machine do? Tap one:
Use your rule: what comes out for 8?
Write the rule in shapes
The number that goes in is ▲, and the number that comes out is ■. The mystery machine adds 4, so its rule is written:
■ = ▲ + 4
That is all a shape equation is — a machine's rule, written in shapes.
Your turn: the take-away machine takes away 3. Tap its shape equation:
Write the rule yourself
Now write the +2 machine's rule in shapes. In is ▲, out is ■ — the machine adds 2.
■ = ▲ +
Build your own machine
Only if everything felt easy! First tap your secret rule:
Now fill in what comes out. Then cover your rule and let Dad guess it from the numbers!
| IN | OUT |
|---|---|
| 5 | |
| 8 | |
| 11 |
You cracked secret numbers, wrote equations in shapes,
and ran function machines.
Stars earned: 0 ⭐
For Dad: harder machines (a missing number on the way IN, doubling, bigger mystery rules) are the next set — when these feel easy.