At least

At least means ‘not less than (but perhaps more than)’. Note that at least is written as two words.

• ‘How old is he?’ ‘At least forty.’
• I phoned him at least six times.
• She has acted in at least twelve films.
• I have written at least ten letters since morning.
• You have eaten at least fifteen chocolates.
• She has lost at least $2000.
• At least twenty people died in the crash.

At least can also be used as a discourse marker.

• Ghosts don’t exist. At least, I haven’t seen one.
• The car was completely damaged in the crash. But at least nobody was hurt.

Not in the least

Not in the least means not at all.

• I was not in the least amused by her antics. (= I was not at all amused by her antics.)
• She is not in the least worried about her safety. (= She is not at all worried about her safety.)
• She is not in the least interested in the proposal.

Using left

Left can mean ‘remaining’, ‘not used’ or ‘still there’.

• I haven’t got any money left. (= I haven’t got any money that I can spend.)
• What did you do with the money that was left?
• There is some milk left.
• We haven’t got any rice left.

Note that left goes at the end of the structure.