Exploding Dots

Choose a mode

Add dots to each box with the − / + buttons (hundreds, tens, ones), or drag up over a box to add. When a box reaches ten dots they explode into one dot in the box to its left. Build the number, then press Check.

3D math game · Best for grades 2-3

Exploding Dots

Exploding Dots turns regrouping into a spectacle. Students place neon dots into ones, tens, and hundreds boxes to represent a target number. When any box reaches ten, those dots explode into one dot in the box to the left — a vivid, rule-free display of why the decimal system works in base ten.

What students practice

Exploding Dots builds deep intuition for base-ten place value. Rather than memorising that ten ones equal one ten, students see it happen as an explosion. This animation-driven understanding of regrouping prepares students for multi-digit addition, subtraction, and eventually number systems in other bases.

  1. Read the target number displayed above the boxes.
  2. Use the −/+ buttons or drag upward to add dots to the ones, tens, or hundreds box.
  3. When a box reaches ten dots, watch them explode into a single dot moving left.
  4. Adjust until the boxes together represent the target number, then press Check.

How to use it at home or in class

Building 23: add 3 dots to the ones box (stays as 3), then add 2 dots to the tens box (stays as 2). No explosions needed. Now build 33: add 13 ones — at ten, they explode into one ten, leaving 3 ones. Result: 1 ten from explosion plus 2 tens added = 3 tens, 3 ones = 33.

Students often overfill a box and miss the explosion, ending up with more than ten dots in one place. The game freezes boxes that overflow until students trigger the explosion, reinforcing that ten-in-one-box is always the rule.

Use it for individual practice, paired work, or a short class demonstration before worksheets.

Start with the game above, then continue with written practice to reinforce the skill.

Common questions

Which grades does Exploding Dots target?
Grades 2–3, where students are establishing place-value intuition for 2-digit and 3-digit numbers and beginning to understand the logic of carrying in addition.
Is this related to James Tanton's Exploding Dots project?
The mechanic is inspired by the same base-ten dot model popularised in mathematics education. The game uses the same visual language to make regrouping self-evident.
How is this different from Addition Mine?
Exploding Dots focuses purely on representing a single number and seeing the explosion rule. Addition Mine uses the same columns but in the context of adding two numbers together with the mine-cart carrying mechanic.