# Preferred double digit divisor mental approach **URL:** https://forum.artofmemory.com/t/preferred-double-digit-divisor-mental-approach/56222 **Category:** Mental Calculation, Mathematics, and Puzzles **Created:** [October 17, 2020, 11:04am UTC](https://forum.artofmemory.com/t/preferred-double-digit-divisor-mental-approach/56222 "2020-10-17T11:04:29Z") **Posts on this page:** 1 **Showing post:** 4
### Author: ![Kinma](https://forum.artofmemory.com/letter_avatar_proxy/v4/letter/k/a88e4f/32.png) [@Kinma](https://forum.artofmemory.com/u/Kinma) #### Post date: [October 21, 2020, 9:06am UTC](https://forum.artofmemory.com/t/preferred-double-digit-divisor-mental-approach/56222/4 "2020-10-21T09:06:08Z")
Hi Tiger. Great to see you back! You and I have discussed division in the past a lost. Starting in 2017. I use a lot of techniques and here is a list of them: > [@Division Mentally](https://forum.artofmemory.com/t/division-mentally/42920/5): > > You might want to google vedic division. > [@Tiger](#): > > Just wondering, do you use this technique when dividing by a 3 digit divisor? Yes, in two steps usually. I think I wrote about it in the past, but could not find it, so let’s do it again. Let’s divide _1000 by 323_. Here goes. 1000/333 = 3. 323 is lower, so try 3 times. Now let’s find the remainder in two steps. 1: 3 times 300 is 900. Subtract from 1000 to get 100. 2: 23 times 3 is 69. Subtract from 100 = 31. If we divide by a number close to a multiple of 100, we can do this slightly different and work with negative numbers. Let’s divide 1000 by 378. Here goes. 1000/333 = 3. 378 is higher, so try 2 times. Now let’s find the remainder in two steps. 1: 2 times 300 is 600. Subtract from 1000 to get 400. 2: 78 is 22 from 100. Subtract 2 times 100 = 200 from 400 and then add 2 times 22 = 44 to get **244**. (We will get back to this remainder later.) Let’s continue working. We now have 2R244. Add a zero: 2440. Try to find a multiple using 400 instead of 378. 2440 goes into 400 about 6 times or 6 time 400 is 2400 and fits in 2440. 2 steps again: 1: 2240 - 6 times 400 =2400 = 40. 2: Add 6 times 22 = 132 to get 172. Add a zero:1720 1720 goes into 400 4 times. 1720 - 1600 = 120. 120 + 4\*22 = 208 Etc, etc. > [@Tiger](#): > > My working memory is stretched trying to remember all the individual parts of the quotient. You might want to experiment with switching 2 steps. Saves one digit in short term memory. Starting from the remainder of **244** : Instead of adding a zero, do the subtraction of the hundreds first. But since we have not added the zero yet, the 400 is now 40 Try to find a multiple using 40. 244 goes into 40 about 6 times or 6 time 40 is 240 and fits in 244. 244 - 240 = 4. Now add the zero. 4 =\> 40. Step 2 is the same as above: 2: Add 6 times 22 = 132. Add to 40 of the previous step to get 172. This can be done in the 323 case as well as above. The remainder is now always 3 digits. Subtract the hundreds first, not forgetting that 378 =\> 400 =\> 40 or that 323 =\> 300 =\> 30. Try this on random numbers and see if it works for you. --- _[View the full topic](https://forum.artofmemory.com/t/preferred-double-digit-divisor-mental-approach/56222)._