Count balls before doing the maths
The over display is a compact scorekeeping label. Under the MCC baseline, an over contains six valid balls. In the usual display, 7.4 means seven completed overs followed by four valid balls of the next over. It represents 46 valid balls, not seven and four tenths of an over. This distinction matters whenever you calculate a rate or compare innings at different stages.
Use a clearly imaginary example
Suppose a practice scoreboard shows 46 runs after 7.4 overs. This is a made-up arithmetic example, not a reported match. Convert the time played to 46 divided by six overs, then divide the runs by that amount. The resulting run rate is 6.00 runs per over. Dividing by the decimal number 7.4 would give a different answer because it uses the wrong unit.
Extra deliveries do not always advance the count
Wides and no-balls do not count among the six valid balls. Other circumstances can also make a delivery invalid, including some dead-ball situations. A sequence of six physical deliveries therefore need not complete an over. Follow the umpire's calls and the official score rather than counting every bowling action yourself.
Keep the rulebook in context
For a beginner, the useful habit is simple: convert completed overs to balls, add the remaining valid balls, and calculate from that total. Tournament playing conditions may add procedures or variations. A scoreboard explanation should identify the competition before making a claim about a particular match.
Factual references
MCC official source 1 ↗MCC official source 2 ↗Original explanatory writing. No official text, images, video or live-score feed is reproduced. References do not imply endorsement.