ANSWER
2.738, 2.74, 2.78, 2.865, 2.867, 2.9
Step-by-step explanation
All of these numbers have the same whole part, 2, so we have to compare the decimals. First, we compare the decimals in the tenths place, then the decimals in the hundredths place, and then the decimals in the thousandths place. We can see all of these as whole 3-digit numbers if we ignore the whole part and the decimal point and add zeros to complete the three digits: 900, 738, 740, 780, 867, 865.
If we put these 3-digit numbers in order from least to greatest we have: 738, 740, 780, 865, 867, 900.
Hence, the list of numbers ordered from least to greatest is 2.738, 2.74, 2.78, 2.865, 2.867, 2.9.