Two straightforward free maths worksheets on counting back in tens from any 2-digit number. By now children should be confident with this, realising that the units digit does not change. If they are finding this difficult a 0-100 number square could be very useful.
Free Y3 maths worksheet: Revise counting back in tens (pg 1)
Free Y3 maths worksheet: Revise counting back in tens (pg 2)