People with Parkinson’s are often asked by doctors to “count backward from 100 by sevens.” I’m never sure if the doctors really want to see if you can do this, or is it just a means of distracting you as they watch what your body is doing during the exercise. However, it turns out that this math problem is also part of one test doctors use to determine if you have Mild Cognitive Impairment.
The mental challenge of this activity struck me, and for a few weeks I thought about it intensely after I turned out the lights and tried to fall asleep. I came up with a method to conquer the problem, and I’ll share it with you here. When I do it now, it’s more like a joyful game than something onerous to get nervous about.
Basically, at each step in the journey, you have to decide if the next task is easy-peasy (in which case you can easily subtract 7) or a headscratcher (in which case you subtract 10 and add 3).
Let’s watch the process:
100
Is 100 – 7 easy-peasy or a headscratcher? It’s easy-peasy, so just do it. 100 – 7 = 93
93
Is 93 – 7 easy-peasy or a headscratcher? It’s a headscratcher. So subtract 10 (93 – 10 = 83) and add 3 (83 + 3 = 86).
86
Is 86 – 7 easy-peasy or a headscratcher? Headscratcher. So subtract 10 (86 – 10 = 76) and add 3 (76 + 3 = 79).
79
Easy-peasy or a headscratcher? Easy-peasy. Just do it. 79 – 7 = 72.
72
Easy-peasy or a headscratcher? Headscratcher. So subtract 10 (72 – 10 = 62) and add 3 (62 + 3 = 65).
65
Easy-peasy or a headscratcher? Headscratcher. Subtract 10 (65 – 10 = 55) and add 3 (55 + 3 = 58).
58
Easy-peasy or a headscratcher? Easy-peasy. Just do it. 58 – 7 = 51
51
Easy-peasy or a headscratcher? Headscratcher. So subtract 10 (51 – 10 = 41) and add 3 (41 + 3 = 44).
44
Headscratcher. So subtract 10 (44 – 10 = 34) and add 3 (34 + 3 = 37)
37
Easy-peasy. Just do it. 37 – 7 = 30
30
Easy-peasy. Just do it. 30 – 7 = 23
23
Headscratcher. Subtract 10 (23 – 10 = 13) and add 3 (13 + 3 = 16).
16
Headscratcher. Subtract 10 (16 – 10 = 6) and add 3 (6 + 3 = 9).
9
Easy-peasy. 9 – 7 = 2
2
Now go buy yourself an ice cream cone. My favorite flavor is mint chocolate chip.
OMG! Thank you 🙂
You’re kidding me. I have become obsessed with counting backwards by sevens. Every time I would be asked this I would be scented to some sort of existential crisis. Then I decided I was going to memorize it. The way I do it is I look at the patterns every set of 10! Either starts with an odd number or an even number. All of the odd numbers have two numbers in them and all of the even numbers just have one. The second digit of the even numbers counts down 8654321. Least I think it does. And I have little trick and mnemonics for the odd numbers. I often go to sleep counting backwards by 7:00. I recently figured out your approach, too. So that’s been smarter and easier than mine. I’ve now gone into negative numbers. Never the math whiz, I’m finding it empowering. I love that you do this. What quirky birds.