MORE REVISION 20040201
This sheet should be done entirely without calculators. The idea is to help you remember some conversions, remember some rules and to apply some skills.
1 The number of grammes in a pound is ____________
2 A mile is _____________________ metres to 4 sig. fig.(no, not seven)
3 There are __________ litres in a gallon (probably 3 sig.fig.)
4 An acre, __________ sq yds, is a c__________ by a f_______________
5 (-23) ² = ___________ 24 ² = ______ -(25) ² = ___________
6 26 ² - 24 ² = 50 x ____ = _____ 29 ² - 21 ² = 8 x ______ =
7 The difference of two squares is …………………… times ………………………
( x ² - y ²) = ( ) ( )
So, without knowing or needing either square, we can work out
8 56² - 44² =
9 76² - 24² =
10 144² - 56² =
and when we do know some squares (up to 30 squared and all ending in 5), then the rule works in reverse, so we can do
11 (29 + 7) (29 - 7)=
12 106 x 94 =
13 88 x 72 =
If you have any time left: treat this as a logical problem, or recognise matrix methods, or both:
14 TRY to fill in the gaps here: 12 x + 7 y = 19 so ( 12 7 )( x ) = ( 19)
3 x + 2 y = -17 ( )( y ) ( )
PREMULTIPLY both ( 2 -7 ) ( 12 7 )( x ) =( 2 ) ( 19)
sides by the same thing ( ) ( 3 )( y ) ( ) ( )
Do matrix multiplication ( 0 ) ( x ) = () = ( )
(I’ve given you enough) ( 0 ) ( y ) ( ) ( )
DIVIDE both sides by ( x ) = ( ) a pair of
the three ( y ) ( ) fractions
