To find the greatest decimal, compare place values from left to right: tens, ones, tenths.

Numbers	=	45.06, 6.564, 40.60, 4.695
Compare tens: 4, 0, 4, 0. 4 is greater. Between 45.06 and 40.60, compare ones: 5 > 0. So 45.06 is the greatest.
Greatest	=	45.06