yuctoborian : a math shortcut for squaring numbers that end in 5
DESCRIPTION
A technique for finding the square of a number that ends in 5.TRANSCRIPT
Squares of halves
1.52 = ( 1 x 2 ) + 0.25 = 2.25
2.52 = ( 2 x 3 ) + 0.25 = 6.25
3.52 = ( 3 x 4 ) + 0.25 = 12.25
4.52 = ( 4 x 5 ) + 0.25 = 20.25
1.52 = ( 1 x 2 ) + 0.25 = 2.25
2.52 = ( 2 x 3 ) + 0.25 = 6.25
3.52 = ( 3 x 4 ) + 0.25 = 12.25
4.52 = ( 4 x 5 ) + 0.25 = 20.25
1.52 = ( 1 x 2 ) + 0.25 = 2.25
2.52 = ( 2 x 3 ) + 0.25 = 6.25
3.52 = ( 3 x 4 ) + 0.25 = 12.25
4.52 = ( 4 x 5 ) + 0.25 = 20.25
1.52 = ( 1 x 2 ) + 0.25 = 2.25
2.52 = ( 2 x 3 ) + 0.25 = 6.25
3.52 = ( 3 x 4 ) + 0.25 = 12.25
4.52 = ( 4 x 5 ) + 0.25 = 20.25
1.52 = ( 1 x 2 ) + 0.25 = 2.25
2.52 = ( 2 x 3 ) + 0.25 = 6.25
3.52 = ( 3 x 4 ) + 0.25 = 12.25
4.52 = ( 4 x 5 ) + 0.25 = 20.25
In other words, multiply the whole numbers above and below the half, then add 0.25.
1.52 = ( 1 x 2 ) + 0.25 = 2.25
2.52 = ( 2 x 3 ) + 0.25 = 6.25
3.52 = ( 3 x 4 ) + 0.25 = 12.25
4.52 = ( 4 x 5 ) + 0.25 = 20.25
In other words,
multiply the whole numbers above and below the half,
1.52 = ( 1 x 2 ) + 0.25 = 2.25
2.52 = ( 2 x 3 ) + 0.25 = 6.25
3.52 = ( 3 x 4 ) + 0.25 = 12.25
4.52 = ( 4 x 5 ) + 0.25 = 20.25
In other words,
multiply the whole numbers above and below the half,
Then add 0.25
Squares of whole numbers ending in 5
152 = 1x2 then attach 25 = 225
252 = 2 x 3 then attach 25 = 625
752 = 7 x 8 then attach 25 = 5625
8052 = 80 x 81 then attach 25 = 648025
152 = 1x2 then attach 25 = 225
252 = 2 x 3 then attach 25 = 625
752 = 7 x 8 then attach 25 = 5625
8052 = 80 x 81 then attach 25 = 648025
152 = 1x2 then attach 25 = 225
252 = 2 x 3 then attach 25 = 625
752 = 7 x 8 then attach 25 = 5625
8052 = 80 x 81 then attach 25 = 648025
152 = 1x2 then attach 25 = 225
252 = 2 x 3 then attach 25 = 625
752 = 7 x 8 then attach 25 = 5625
8052 = 80 x 81 then attach 25 = 648025
Squares of decimal numbers ending in 5
0.752 = 7 x 8, then attach 25 = 5625
0.752 = 7 x 8, then attach 25 = 5625
(But where does the decimal point go?)
0.752 = 7 x 8, then attach 25 = 5625
(But where does the decimal point go?)
The number is ‘three-quarters of three-quarters.’
That has to be close to ½.
0.752 = 7 x 8, then attach 25 = 5625
(But where does the decimal point go?)
The number is ‘three-quarters of three-quarters.’
That has to be close to ½.
(But where does the decimal point go?)
0.752 = 7 x 8, then attach 25 = 0.5625
1.052 = 10 x 11 then attach 25 = 11025
0.752 = 7 x 8, then attach 25 = 0.5625
1.052 = 10 x 11 then attach 25 = 11025
The answer has to be slightly larger than 1.
0.752 = 7 x 8, then attach 25 = 0.5625
1.052 = 10 x 11 then attach 25 = 1.1025
0.752 = 7 x 8, then attach 25 = 0.5625
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