Kani Math
Cosmic Abacus
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One-digit addition drills

Five single digits per column. Short enough for a five-year-old, long enough that memorised answers stop working.

  • 5 rows × 1 digits, addition
  • About 5 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
    3
    + 7
    + 9
    + 7
    + 9
    ?
  2. 2
    4
    + 6
    + 7
    + 9
    + 5
    ?
  3. 3
    1
    + 8
    + 4
    + 5
    + 7
    ?
  4. 4
    5
    + 7
    + 6
    + 4
    + 2
    ?
  5. 5
    2
    + 5
    + 8
    + 2
    + 7
    ?
  6. 6
    4
    + 2
    + 3
    + 9
    + 3
    ?
  7. 7
    2
    + 5
    + 6
    + 5
    + 8
    ?
  8. 8
    9
    + 6
    + 7
    + 3
    + 9
    ?
  9. 9
    1
    + 6
    + 4
    + 2
    + 1
    ?
  10. 10
    3
    + 7
    + 3
    + 8
    + 4
    ?
Full answer key
  1. 3 + 7 + 9 + 7 + 9 = 35
  2. 4 + 6 + 7 + 9 + 5 = 31
  3. 1 + 8 + 4 + 5 + 7 = 25
  4. 5 + 7 + 6 + 4 + 2 = 24
  5. 2 + 5 + 8 + 2 + 7 = 24
  6. 4 + 2 + 3 + 9 + 3 = 21
  7. 2 + 5 + 6 + 5 + 8 = 26
  8. 9 + 6 + 7 + 3 + 9 = 34
  9. 1 + 6 + 4 + 2 + 1 = 14
  10. 3 + 7 + 3 + 8 + 4 = 25

This page is one drill. The app is the whole programme.

Kani Math is a full mental-arithmetic course, not a single exercise. Free to start, no signup, and it runs on the web, Android and iPhone.

  • ✓Nine levels, from the first bead to division
  • ✓Four timed sprints and two practice exams, with leaderboards
  • ✓Flash, listening and abacus drills at a speed you set
  • ✓Versus matches against friends or the computer
  • ✓Say your answers out loud — the app listens and marks them
  • ✓Streaks, coins and badges, a teacher view, and a parent dashboard with Premium
Nine levels, one skill at a time.
Math Sprint — solve against the clock.
A weekly progress view for parents.

Want to stay here? The demo further down runs right on this page.

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Practise it now

A live drill of the same shape, in your browser, with a virtual soroban and instant marking.

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Loads a full interactive drill right here on the page. It never asks who you are.

No signup. Nothing saved unless you ask.

Explore the free virtual abacus →How to use an abacus →Mental Math Drill →

About this drill

Single-digit addition is the drill everyone starts with and almost everyone under-practises. Two-term sums get memorised quickly — 6 + 7 becomes a fact, not a calculation — which feels like progress but trains nothing. Five terms in a column cannot be memorised, so the learner has to actually maintain a running total, and that is the skill that carries forward.

Every problem below is pure addition with no negative steps, and the running total climbs past 9 in almost every column, so carrying is part of the exercise. That makes it a good warm-up for a learner who already knows big friends, on beads or entirely in the head.

How to practise it

  1. 1Read the full column once before starting.
  2. 2Add top to bottom at a steady pace, one number per beat.
  3. 3Do not say the running total out loud — hold it.
  4. 4Check the answer only after the last row.

Questions

Is this suitable for a complete beginner?
Not as a first exercise. Five single digits add up past 9 in almost every column, so most columns need a carry (big friends) and some need both friends at once. A complete beginner should start with the counting and one-digit pages, then come here.
Should my child use fingers?
For a short while it is fine, but it caps speed at roughly one number per second forever. Beads or a mental image both scale; fingers do not.
How many columns per session?
Ten to twenty is a good daily dose at this width. Short and daily beats long and weekly by a wide margin.
What comes next?
Two-digit addition, or the 5-complement rules if you want the abacus technique rather than more of the same arithmetic.
Learn the techniqueSmall friends (5-complements)Walk through it on the beads →