Kani Math
Cosmic Abacus
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Ten-row addition drills

The classic exam column: ten numbers, one answer, and no way to check your work partway through.

  • 10 rows × 2 digits, addition
  • About 10 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
    74
    + 47
    + 32
    + 30
    + 69
    + 68
    + 80
    + 28
    + 42
    + 83
    ?
  2. 2
    45
    + 67
    + 84
    + 94
    + 59
    + 42
    + 44
    + 84
    + 60
    + 22
    ?
  3. 3
    42
    + 70
    + 71
    + 93
    + 69
    + 16
    + 85
    + 92
    + 75
    + 17
    ?
  4. 4
    34
    + 88
    + 64
    + 88
    + 81
    + 79
    + 95
    + 14
    + 39
    + 71
    ?
  5. 5
    52
    + 47
    + 62
    + 94
    + 85
    + 71
    + 90
    + 82
    + 99
    + 26
    ?
  6. 6
    71
    + 13
    + 78
    + 25
    + 36
    + 84
    + 58
    + 74
    + 27
    + 55
    ?
  7. 7
    22
    + 72
    + 94
    + 54
    + 41
    + 29
    + 37
    + 17
    + 94
    + 35
    ?
  8. 8
    40
    + 46
    + 71
    + 83
    + 57
    + 33
    + 49
    + 45
    + 48
    + 38
    ?
Full answer key
  1. 74 + 47 + 32 + 30 + 69 + 68 + 80 + 28 + 42 + 83 = 553
  2. 45 + 67 + 84 + 94 + 59 + 42 + 44 + 84 + 60 + 22 = 601
  3. 42 + 70 + 71 + 93 + 69 + 16 + 85 + 92 + 75 + 17 = 630
  4. 34 + 88 + 64 + 88 + 81 + 79 + 95 + 14 + 39 + 71 = 653
  5. 52 + 47 + 62 + 94 + 85 + 71 + 90 + 82 + 99 + 26 = 708
  6. 71 + 13 + 78 + 25 + 36 + 84 + 58 + 74 + 27 + 55 = 521
  7. 22 + 72 + 94 + 54 + 41 + 29 + 37 + 17 + 94 + 35 = 495
  8. 40 + 46 + 71 + 83 + 57 + 33 + 49 + 45 + 48 + 38 = 510

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
  • ✓Guided lessons that teach the technique, not just drills
  • ✓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, with parent and teacher views

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

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Practise it now

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

About this drill

Ten-row columns are the standard unit of assessment in abacus training, and they measure something the shorter drills do not: whether a learner can hold procedure and attention together for twenty consecutive seconds. The arithmetic is easy — two-digit addition, no subtraction — and yet accuracy on these is consistently lower than on much harder short problems.

That gap is the whole point. If your accuracy drops on long columns while staying high on short ones, the problem is not technique and more rule practice will not fix it. Practise the length itself.

How to practise it

  1. 1Sit properly and clear the desk before you start — this drill punishes fidgeting.
  2. 2One row per beat, and never break the beat.
  3. 3Do not verify the running total at any point.
  4. 4Log the score; long-column accuracy improves visibly week over week.

Questions

Why is my accuracy worse here than on harder problems?
Because length, not difficulty, is what these test. Twenty seconds of unbroken attention is a separate skill from knowing the rules.
Should I write down intermediate totals?
No. The abacus holds the total; writing it down reintroduces exactly the dependency the method removes.
How many should I do at once?
Eight is a full set. Accuracy on long columns falls off sharply with fatigue, so a longer session mostly produces bad data.
Is there a time limit?
In examinations, yes. For practice, no — build accuracy at a steady pace first and let speed follow.
Learn the techniqueBig friends (10-complements)Walk through it on the beads →