Question

Write six hundred thirty-four thousandth in decimal notation

Answer 1

so if you mean in decimals then

0.1 is 1/10 or tenth
0.01 is 1/100 or hundreth
0.001 is 1/1000 or thousandth
so 6 hundred 34 thousandths or 634/1000 or
0.634

Answer 2

0.634 would be the correct answer - it's easier if you know your place values :)