140 Characters ...

Thank you, Dork Tower - and quite possibly Zho Berka's LBB generator, too. :)

And to the vast chunk of my f'list who have never played Traveller, never mind. In joke.

140 Characters ...

Thank you, Dork Tower - and quite possibly Zho Berka's LBB generator, too. :)

Welcome to Dreamwidth, lemuria. :)

It's Been A While ...

Until the previous entry, 140 Characters, it has been more than a year since I posted here.

Sorry about that.

Let's make up for lost time, eh?

Mental Arithmetic - Tables of Numbers

Here are some basic tables of numbers. Copy and paste them to your own computer, print them out, save them in a spreadsheet if you will - you'll be coming back to them over and over to practice different techniques.

These figures start with single digits, then move on to digit pairs, then three digit figures, four digit numbers and so on up to eight digit numbers. Don't let the size of the numbers daunt you: you're practicing on individual digits, or on digit pairs, and you only need concentrate on a handful of digits at any one time.

In fact, the longer the number the more practice you can get working those digits, to give some of the longer numbers a go. You could get better at it, faster.

These tables can be used for all the following exercises. Whether we'll be multiplying by a small number like 12, or doing multiplication by a longer number like 3342, or even dividing numbers, you can come back to these particular numbers to work on your techniques.

Use them as metrics. If you become familiar with multiples of, say, 32447, you'll know if you're in the right ballpark before you check your multiplications or whatever.

And now, the tables.

"Halving" Digits

Digit	"Halved"
0, 1	0
2, 3	1
4, 5	2
6, 7	3
8, 9	4

Single Digits

5	1	3	2	7	5	8	1	6	2
0	9	2	5	1	3	4	1	9	6
7	1	0	4	8	4	7	2	9	3

Digit Pairs

4 8	2 7	1 8	4 5	5 2	8 3	6 7	6 9	9 1	8 0
0 9	1 2	3 6	2 7	9 4	8 6	2 5	6 1	4 2	1 7
7 6	6 4	3 5	1 8	5 1	6 9	0 4	2 7	2 6	4 7

Three-Digit Numbers (+leading zero)

0709	0475	0154	0216	0352
0198	0847	0729	0117	0263
0229	0886	0212	0261	0811
0702	0260	0699	0370	0435
0735	0579	0545	0873	0567
0378	0456	0112	0396	0440

Four-Digit Numbers (+leading zero)

08295	09922	01666	08602	09132
06556	07078	09709	02930	08240
02737	07688	03580	05584	05142
04683	05616	03905	08808	05275
06757	09965	09897	03830	06388
05187	01451	02731	05777	03304

Five-Digit Numbers (+leading zero)

039447	039232	040222	034251	052497
070452	067924	003561	070302	051801
040681	038163	087386	058424	065359
033770	097925	058764	030034	091426
027759	062257	076715	083982	045638
038841	010937	088876	037494	080149

Six-Digit Numbers (+leading zero)

0836325	0341267	0136900	0963637	0988439
0335986	0902530	0119677	0901084	0724990
0298444	0958696	0521690	0555354	0930256
0994412	0275789	0695617	0803280	0814464
0383324	0760391	0143876	0819288	0358038
0110864	0434222	0301688	0697005	0853435

Seven-Digit Numbers (+leading zero)

06116226	03742111	02957124	07702730	03379118
06953976	05488932	01253347	08449990	05232484
02173108	06821219	08484185	08952742	04273777
03271728	00137663	03621897	03826997	02584635
06577286	08806829	04317546	06988269	05336647
01393093	08899358	05471934	02020510	03155663

Eight-Digit Numbers (+leading zero)

058813130	038911530	061881803	058810146	020924136
016106911	076754100	091432881	020621010	036049099
034343877	033676744	015682998	088816350	072154062
034473246	095580429	043694589	045871914	054246060
092505926	055630386	097448373	044481475	028921487
043236483	058611859	016358692	034893653	027001188