Final answer:
To put the numbers in order from largest to smallest, compare the numbers and arrange them accordingly.
Step-by-step explanation:
To put the numbers in order from largest to smallest, we compare the numbers and arrange them accordingly:
1.21 > 0.121 > 0.1 > 0.0121
So, the numbers in order from largest to smallest are: 1.21, 0.121, 0.1, 0.0121.