IF THE INITIAL VALUE OF A SEQUENCE IS 6 AND THE COMMON DIFFERENCE IS 6, WHAT IS THE 7TH ELEMENT?
Using the formula where a0 is the initial value and an is the 'nth' term, while 'd' is the common difference:
a7 = a0 + (n-1) x d = 6 + (7-1) * x 6 = 6 + 36 = 42
QED