# fun math tricks/calculator tricks

## Overview

here's some fun for teens to try with a calculator. there is a limit on calculators as to the number of digits however. I am using ttcalc for the big numbers calculations.

## Symmetries #1

```121×9=1089
12321×9=1089
```
```01210×9=10890
0123210×9=1108890
012343210×9=111088890
0123454210×9=11110888890
012345654210×9=111110887890
01234567654210×9=11111108887890
0123456787654210×9=1111111088887890
012345678987654210×9=111111110888887890
```
```21012×9=189108
3210123×9=28891107
432101234×9=3888911106
54321012345×9=488889111105
6543210123456×9=58,888891111104
765432101234567×9=6888888911111103
87654321012345678×9=788888889111111102
9876543210123456789×9=88888888891111111101
```
```212×9=1908
32123×9=289107
4321234×9=38891106
543212345×9=4888911105
65432123456×9=588889111104
7654321234567×9=68888891111103
876543212345678×9=7888888911111102
98765432123456789×9=888888889111111101
```
```21098765432123456789012×9=189888888889111111101108
456789876543212345678987654×9=4111108888888911111110888886
```

## 2-4-2012: 10-key keypad patterns - fun calculator tricks

```15315×57957=887611455
5693+5417=1110
5213+5897=1110 (same even when turned 90°)
54125+52365+56985+58745=222220
52145+56325+58965+54785=222220 (same when going ccw or cw)
```

God showed me this first one right off. no other multiplication pattern I tried worked. I asked him to. there was one other one God showed me a long time ago, but this one is lost. I think it involved patterns like 183729761349 or something like that: triangles on the 10-key, and I ended up with some really cool numbers - but I don't remember exactly what I did, and the web page got lost it involved maybe multiplication, or possibly also addition and subtraction!

## 4-6-2010 operator sequencing

was playing with my mother's calculator, and God gave me this little calculator sequence/equation first time without thinking. do this on a calculator:

I think God was showing this to me. this happens once in a while.

it's something fun for kids to try on a calculator. press these keys:

1+2×3-4÷5= (result is 1). fun isn;'t it? numerically interesting too.

properties:

• you end up with the same number you started with
• the numbers you enter are all in sequence from 1 to 5.
• for a four-function calculator, it uses all the operators (function keys) exactly once.
• the operators are grouped in the following pattern:
• grouped in pairs.
• first pair is positive operator and positive succession operator
• second pair is negative operator and negative succession operator
• each pair starts with the lower order/priority operator first, followed by the higher order/priority operator next.
• operator groups are sorted, if you wish to think of it that way.

This does not work in equation editors, but only in an equation editor. Now that I look at it, the equivalent equation would be: ((1+2)×3-4)/5=1. Once you look at it, it becomes:

$( 1 + 2 ) × 3 - 4 5 = 3 × 3 - 4 5 = 9 - 4 5 = 5 5 = 1$