02 824 365
Antidotia
Antidotia
Antidotia

Station  10
Subtraction 

Let's use the antidots we've just created to examine subtraction.

Question 1

Consider this subtraction problem.

I4S10-image12

To me, this is really 536536 plus the opposite of 123123.
That is, we're adding one anti-hundred, two anti-tens, and three anti-ones to five hundreds, three tens and six ones.

Put the numbers 536536 and 123-123 into a 1101\leftarrow 10 machine.

loader

Question 2

Make the annihilations required to show the value of 413413.

loader

Question 3

Try this problem on the machine!
I4S10-image22

loader

Question 4

Unexplode some dots to clarify the result of the subtraction.

loader

Question 5

Here’s a very long subtraction problem. Compute it the dots and antidots way and then fix up your answer for society’s sake.

Thinking Question: As you fix up your answer for society, does it seem easier to unexplode from left to right or from right to left?

I4S10-image40b

All correct approaches to mathematics are correct – even this strange approach to subtraction. Actually, if you click on the station below about the Traditional Algorithm, you will see my approach here isn’t actually that new or different!

Antidotia
Vision byPowered by
Contact GMP:
  • The Global Math Project on Twitter
  • The Global Math Project on Facebook
  • Contact The Global Math Project
Contact BM:
  • Buzzmath on Twitter
  • Buzzmath on Facebook
  • Visit Buzzmath's Website
  • Read Buzzmath's blog!