Numbers appear one at a time and vanish. Nothing stays on screen, so nothing can be re-read — the total lives in your head or nowhere.
4 rows × 2 digits, add & subtract
About 6 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
71
+ 28
+ 69
+ 50
?
2
76
− 72
+ 64
+ 39
?
3
10
+ 81
+ 89
+ 13
?
4
81
+ 47
− 21
+ 93
?
5
12
+ 66
+ 18
+ 16
?
6
37
+ 78
+ 27
+ 17
?
7
17
+ 94
+ 34
+ 70
?
8
36
+ 76
+ 10
− 32
?
9
16
+ 85
+ 45
− 66
?
10
88
− 51
− 29
+ 34
?
Full answer key
71 + 28 + 69 + 50 = 218
76 − 72 + 64 + 39 = 107
10 + 81 + 89 + 13 = 193
81 + 47 − 21 + 93 = 200
12 + 66 + 18 + 16 = 112
37 + 78 + 27 + 17 = 159
17 + 94 + 34 + 70 = 215
36 + 76 + 10 − 32 = 90
16 + 85 + 45 − 66 = 80
88 − 51 − 29 + 34 = 42
Practise it now
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About this drill
A printed column can be re-read. A flash card cannot. That single difference changes what is being trained: with a column, a learner can recover from a lapse by glancing back; with flashed numbers, a lapse ends the problem. The exercise stops being about arithmetic and becomes about maintaining a value under time pressure.
Flash cards are also the cleanest way to break a learner off finger counting and written intermediates, because neither is fast enough to keep up. Start slow — two seconds per number is plenty — and shorten the interval only when accuracy holds.
How to practise it
1Set the interval slow enough that accuracy stays at 100%.
2Look at the centre of the screen, not at each number.
3Update the running total on every flash; never let one pass unprocessed.
4Shorten the interval by a fraction only after a clean full set.
Questions
What is the difference between flash cards and flash anzan?
Flash cards are the format; flash anzan is flash cards worked on a mentally visualized abacus. You can use flash cards with beads in front of you, and many learners do at first.
What interval should we start at?
Two seconds per number. Anything faster while accuracy is still settling just trains guessing.
My child does well on paper but badly here.
That is the normal pattern, and it means paper work was leaning on re-reading. A few weeks of flash practice usually closes it.
Are these the same as multiplication flash cards?
No. Standard flash cards test recall of a single fact. These test maintaining a running total across several numbers, which is a different skill.