Kani Math
Cosmic Abacus
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Multi-row addition practice (10 rows)

Ten numbers, one column, no pauses. This is where accuracy stops being about knowing the rules and starts being about not losing concentration.

  • 10 rows × 2 digits, add & subtract
  • 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
    88
    − 19
    + 42
    − 60
    + 83
    + 54
    + 60
    + 66
    − 65
    − 75
    ?
  2. 2
    29
    + 26
    + 16
    + 35
    + 38
    + 67
    + 32
    − 98
    − 71
    − 17
    ?
  3. 3
    71
    − 26
    + 10
    + 35
    + 87
    − 51
    + 38
    − 28
    + 67
    + 18
    ?
  4. 4
    37
    + 64
    + 28
    − 54
    − 23
    + 20
    + 50
    − 38
    + 90
    − 44
    ?
  5. 5
    68
    + 60
    − 73
    + 65
    + 26
    + 58
    − 39
    + 46
    + 66
    − 64
    ?
  6. 6
    35
    + 91
    + 49
    + 87
    + 98
    + 24
    − 93
    − 44
    − 37
    + 95
    ?
  7. 7
    10
    + 45
    + 70
    + 32
    − 18
    + 55
    + 65
    + 72
    + 50
    − 62
    ?
  8. 8
    23
    + 47
    + 74
    + 87
    + 85
    − 55
    + 85
    + 27
    − 65
    + 98
    ?
Full answer key
  1. 88 − 19 + 42 − 60 + 83 + 54 + 60 + 66 − 65 − 75 = 174
  2. 29 + 26 + 16 + 35 + 38 + 67 + 32 − 98 − 71 − 17 = 57
  3. 71 − 26 + 10 + 35 + 87 − 51 + 38 − 28 + 67 + 18 = 221
  4. 37 + 64 + 28 − 54 − 23 + 20 + 50 − 38 + 90 − 44 = 130
  5. 68 + 60 − 73 + 65 + 26 + 58 − 39 + 46 + 66 − 64 = 213
  6. 35 + 91 + 49 + 87 + 98 + 24 − 93 − 44 − 37 + 95 = 305
  7. 10 + 45 + 70 + 32 − 18 + 55 + 65 + 72 + 50 − 62 = 319
  8. 23 + 47 + 74 + 87 + 85 − 55 + 85 + 27 − 65 + 98 = 406

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.

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About this drill

Intermediate A adds one move and a lot of length. The move is both friends at once: when the partner a big friend takes off cannot come off directly, it comes off as a small friend, as in 6 + 7 = 13 — ten on the left rod, then the five-bead up and two earth beads up (+7 = +10 − 5 + 2). The rest is stamina. A ten-row column contains roughly twenty bead decisions, and a single lapse anywhere in the sequence destroys the answer with no warning and no way to spot it afterwards. This is the level where children learn that abacus accuracy is a property of attention, not of arithmetic.

Practise these at a steady rhythm rather than as fast as possible. Speed on long columns comes from never stopping, not from moving quickly — a learner who works at a metronome pace and never re-reads a row will beat a faster one who hesitates twice.

How to practise it

  1. 1Set a steady beat — one row per beat, out loud or with a metronome.
  2. 2Never re-read a row you have already added.
  3. 3If you lose the total, stop and restart the column; do not guess.
  4. 4Check the answer once at the end, not partway through.
Where this sits

Level 5 — Intermediate A

Multi-row addition with mixed complements.

Teaches: Multi-row addition, mixed 5/10-complement combinations

Find your level with the free placement exam →

Questions

Why ten rows specifically?
It is the standard column length in abacus examinations and competitions, long enough to test concentration and short enough that a mistake does not cost several minutes.
Should the running total be checked partway?
No. Checking mid-column trains the habit of doubting, which costs more accuracy over time than the occasional lost problem.
Is this still done on beads or in the head?
On beads at this level. Mental visualization starts properly at the next stage, once ten-row accuracy on the physical abacus is reliable.
How many columns per session?
Eight to ten is plenty. Long-column work is tiring in a way single-digit drills are not, and accuracy collapses well before boredom does.
Learn the techniqueBig friends (10-complements)Walk through it on the beads →