@Peter-Wilcox
Depending on what you are doing you can also use the google fit app (strenth training work out).
It will auto detect the exercise (sit up, press up, curls etc) - if it doesn’t detect it you can add the exercise and it often will then auto-detect it going forward (depends on the action).
It will auto-detect the number of reps and sets (you can also manually adjust if mis-counts)
If using weights you can add that weight used.
And between each set there is an interval time which you, skip, change etc.
Afterwards google fit will show each exercise, number of sets and reps.
May or may not suite depending on what you are doing.