Math w/o calculator :
Next find product of 25 and 35.
Tricky. Rounding and multiplying the first digits give 1200. Possibly not correct.
Lets use log tables from memory. No calculator or log chart. We can only get two significant digits.
log of 2.5 = 40
log of 3.5 = 53
Adding we get 93.
Anti log from memory : 8.7
Therefore ans : 870.
Real ans : 875
We achieved two digit significance, from memory.
cont... calculating log inside your head.
- Comments:
- PC only. Androids use apps for these cases. You can save the dictionary page as a link on your home screen - touch to open it - and type in, submit to search.... just the same.
- ^ I follow this for frequently accessed pages on mobile.