Vedic Maths – Multiplying Numbers Near a Base
MULTIPLYING NUMBERS NEAR A BASE
To multiply, say, 88 by 98 we observe that these numbers are close to the base of 100 and once again we obtain the answer by one line mental arithmetic:
We see that 88 is 12 below 100 and 98 is 2 below, as shown.
Cross-subtracting we get 88-2 = 86 (or 98-12 = 86) for the first part of the answer,
and multiplying vertically we get 12×2 = 24 for the second part.
So 88 × 98 = 8624.
There are a large number of variations of this method which render it applicable in many other situations (Williams & Gaskell, 1997).
Vertically and Crosswise has a huge range of applications- and remember it is just one of sixteen formulae used in Vedic Mathematics!
The Vedic system is extremely coherent and unified, the methods are so easy they really amount to mental arithmetic. A full Vedic Mathematics course covering the National Curriculum for Key Stage 3 is now available and is being successfully used in some schools. (Williams & Gaskell, 1998)