## Time & distance

Average Speed Average speed is always equal to total distance travelled to total time taken to travel that distance.Average speed=Total distanceTotal timeAverage speed=Total distanceTotal time Distance ConstantIf distance travelled for each part of the journey, ie d1=d2=d3=…=dn=dd1=d2=d3=…=dn=d, then average speed of the object is Harmonic Mean of speeds.Let each distance be covered with speeds s1,s2,…sns1,s2,…sn in t1,t2,…tnt1,t2,…tn times respectively.Then t1=ds1t1=ds1, t2=ds2t2=ds2, … tn=dsntn=dsnAverage Speed=d+d+d+…ntimes(ds1)+(ds2)+(ds3)+…(dsn)Average…

## Multiple of a number ending with 5

A number that ends in 5 can be written as 10x + 5 or 10y + 5. So we multiply those factors and re-group. The term xy + (x + y)/2 means to add the product and the average of the leading digits. Then you multiply by 100 and finally add 25. 1– Add the…

## Squaring of a number ending with 5

You can square numbers ending in 5 the same way you square other numbers. A quick way to square any number is by using a calculator; however, when you are squaring a two-digit number ending in 5, you can use an easy method without the aid of a calculator. For a two-digit number with the…