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K
Kani
Cosmic Abacus
🎧

Listening mental math practice

Nothing on screen. The numbers are spoken, the abacus is imagined, and the answer is said out loud.

  • 5 rows × 1 digits, add & subtract
  • About 7 min
  • Free, no account

Sample problems

Real problems from this drill, with answers. Nothing to install, no account, no email — work them on paper, on a physical abacus, or in your head.

  1. 1
    8
    + 4
    + 6
    + 1
    − 6
    ?
  2. 2
    1
    + 3
    + 7
    + 9
    + 1
    ?
  3. 3
    4
    + 1
    + 8
    + 7
    + 9
    ?
  4. 4
    2
    + 6
    − 4
    + 5
    + 6
    ?
  5. 5
    9
    − 1
    + 2
    + 9
    − 6
    ?
  6. 6
    4
    + 1
    − 3
    + 7
    − 4
    ?
  7. 7
    6
    − 4
    − 1
    + 8
    − 2
    ?
  8. 8
    5
    − 1
    + 6
    + 7
    + 9
    ?
  9. 9
    8
    + 3
    + 7
    − 2
    − 1
    ?
  10. 10
    1
    + 4
    + 3
    − 2
    − 6
    ?
Full answer key
  1. 8 + 4 + 6 + 1 − 6 = 13
  2. 1 + 3 + 7 + 9 + 1 = 21
  3. 4 + 1 + 8 + 7 + 9 = 29
  4. 2 + 6 − 4 + 5 + 6 = 15
  5. 9 − 1 + 2 + 9 − 6 = 13
  6. 4 + 1 − 3 + 7 − 4 = 5
  7. 6 − 4 − 1 + 8 − 2 = 7
  8. 5 − 1 + 6 + 7 + 9 = 26
  9. 8 + 3 + 7 − 2 − 1 = 15
  10. 1 + 4 + 3 − 2 − 6 = 0

Practise it now

The same drill, live in your browser, with a virtual soroban and instant marking.

This problem type runs in the full app rather than the inline drill:

Open in the app ↗

About this drill

Listening drills — read anzan in the Japanese tradition — remove the visual channel entirely. The learner hears each number, converts it to a bead movement, and never sees a digit. This is harder than flash practice for most people, because the conversion from sound to bead image has no visual anchor to lean on.

It is also the format that transfers most directly to everyday life, where numbers arrive spoken far more often than written: prices at a counter, scores called out, a phone number read aloud. A learner who can only add what they can see has half a skill.

How to practise it

  1. 1Use headphones or a quiet room — this drill is unusable with background noise.
  2. 2Close your eyes if it helps hold the bead image.
  3. 3Move the imagined beads on the sound, not after it.
  4. 4Say the answer aloud before checking it.

Questions

What language are the numbers spoken in?
English, in every locale. Number narration is deliberately a single audio set — a mixed-language drill teaches the learner to translate, which is exactly the verbal detour the method removes.
Why is listening harder than seeing?
Because sound is transient and sequential. A flashed digit still leaves a brief visual trace; a spoken one leaves nothing once it ends.
Can I do this without a mental abacus?
You can add spoken numbers verbally, but it caps out quickly. The whole advantage here comes from converting sound straight to bead image without a verbal middle step.
Does the voice input need a microphone?
Only if you want to answer by speaking. Typing the answer works everywhere and needs no permissions.