Transcutaneous electrical nerve stimulation (TENS) is a technique that applies electrical current to nerves and muscles for the relief of pain. Before you ask, yes, some of these devices are FDA ...
Eg, units become thousands. Note: units are often referred to as ones. For example, 34 has 3 tens and 4 units, or we could say 34 has 3 tens and 4 ones. Write 18 out with place value labels.