No pen/pencil .
No paper .
No calculator .
Just your brain and a timer/stopper/wristwatch.
Start timer NOW.
Put your hands in your pockets and start reading:
Let A=160*35 & B=1400*4
DECIDE, WHICH IS BIGGER (3 CHOICES):
a. B
b. A
c. the same
After deciding upon your answer, take your hands out of your pockets and
-write down your answer
-and the time elapsed.
It took me longer - 15-20 sec. Here was my approach. 1st - are all powers of 10 unimportant? To check, separately approximate both A & B.
A: 1.6 * 3500, which is like 1.5 * 3500, and is ballpark 5000 to 6000
B: 4 * 1400 is a bit less than 4 * 1500, so again ballpark 5000 to 6000
So we forget powers of 10 and just work with numbers.
3.5 and 14 are related by 4, and so with two "4s" on the left (16) and one on the right - we are in equilibrium. Done. Equal.
Edited on January 14, 2020, 11:43 pm
how (my way)
