Mental Math with Tricks and Shortcuts (continued)

Mental Math with Tricks and Shortcuts (continued)

Cube Roots the Long Way

(636056)^1/3

What number cubed is less than 636 = 8. Put 8 down as first part of answer

Square 8 for 64 and multiply by 300 = 19200. Divide into 114056 = 6, add the 8 and 6 = 14

Multiply 14 x 30 = 420, add 420 to 19200 = 19620, square the 6 and add to 19620 = 19656

If 6 x 19656 is less than 124056, then it is not necessary to use lower number.

636 056 = 86³

512

19656)124056

117936

----------------

7120

USE ESTIMATES

Use estimates to check your answers. Get in the habit of doing this for all calculations.

NOTE: Considerable care has been taken to eliminate errors in this document, but the author does not

guarantee that the document is error free by implication or in fact.