Rekenen met datum en tijd

Aangezien \(t = 0\) overeenkomt met 1 januari, komt \(t = 309\) overeen met \(310 \text{ } \text{januari} \text{.}\)

\(310 \text{ } \text{januari}\)
\(\text{ } = 310 - 31 \text{ (januari)} = 279 \text{ } \text{februari}\)
\(\text{ } = 279 - 28 \text{ (februari)} = 251 \text{ } \text{maart}\)
\(\text{ } = 251 - 31 \text{ (maart)} = 220 \text{ } \text{april}\)
\(\text{ } = 220 - 30 \text{ (april)} = 190 \text{ } \text{mei}\)
\(\text{ } = 190 - 31 \text{ (mei)} = 159 \text{ } \text{juni}\)
\(\text{ } = 159 - 30 \text{ (juni)} = 129 \text{ } \text{juli}\)
\(\text{ } = 129 - 31 \text{ (juli)} = 98 \text{ } \text{augustus}\)
\(\text{ } = 98 - 31 \text{ (augustus)} = 67 \text{ } \text{september}\)
\(\text{ } = 67 - 30 \text{ (september)} = 37 \text{ } \text{oktober}\)
\(\text{ } = 37 - 31 \text{ (oktober)} = 6 \text{ } \text{november}\)

Aangezien \(t = 0\) overeenkomt met 12 april 2022, komt \(t = 81\) overeen met \(12 + 81 = 93 \text{ } \text{april} \text{.}\)

\(93 \text{ } \text{april}\)
\(\text{ } = 93 - 30 \text{ (april)} = 63 \text{ } \text{mei}\)
\(\text{ } = 63 - 31 \text{ (mei)} = 32 \text{ } \text{juni}\)
\(\text{ } = 32 - 30 \text{ (juni)} = 2 \text{ } \text{juli}\)
Dus bij \(t = 81\) hoort 2 juli 2022.

7 september 2021 is \(t = 0\)
30 september 2021 is \(t = 30 - 7 = 23\)
31 oktober 2021 is \(t = 23 + 31 = 54\)
23 november 2021 is \(t = 54 + 23 = 77\)

\(t = 40\) komt dan overeen met \(\text{1960} + 40 = \text{2000} \text{.}\)

\(\text{2017}\) komt dan overeen met \(t = \text{2017} - \text{1997} = 20 \text{.}\)

De maand augustus heeft \(31\) dagen.

De \(11\)e maand van het kalenderjaar is \(\text{november} \text{.}\)

Op \(t = 7{,}506\) is het \(7 \text{ } \text{uur}\) en \(0{,}506 ⋅ 60 = 30{,}36 \text{ } \text{minuten}\) later dan \(\text{1:00} \text{ } \text{uur} \text{.}\)
Het is dan dus \(\text{8:30} \text{ } \text{uur} \text{.}\)

Om \(\text{22:14} \text{ } \text{uur}\) is het \(10 \text{ } \text{uur}\) en \(14 \text{ } \text{minuten}\) later dan \(\text{12:00} \text{ } \text{uur} \text{.}\)
Dat is dus bij \(t = 10 + {14 \over 60} = 10{,}23333... \text{.}\)

\(6{,}1 \text{ } \text{uren} = 6{,}1 ⋅ 60 \text{ } \text{minuten} = 366 \text{ } \text{minuten}\)

\(40\,680 \text{ } \text{seconden} = 40\,680 : 3\,600 \text{ } \text{uren} = 11{,}3 \text{ } \text{uren}\)

\(0{,}53 \text{ } \text{minuten} = 0{,}53 ⋅ 60 = 31{,}8 \text{ } \text{seconden} \text{,}\) dus \(1{,}53 \text{ } \text{minuten} = 1 \text{ } \text{minuten}\) en \(32 \text{ } \text{seconden} \text{.}\)

\(9 \text{ } \text{jaar}\) en \(8 \text{ } \text{maanden} = 9 + {8 \over 12} = 9{,}666... \text{ } \text{jaar} \text{.}\)

\(2 \text{ } \text{dagen} = 2 ⋅ 24 ⋅ 3\,600 = 172\,800 \text{ } \text{seconden}\)
\(15 \text{ } \text{uren} = 15 ⋅ 3\,600 = 54\,000 \text{ } \text{seconden}\)
\(52 \text{ } \text{minuten} = 52 ⋅ 60 = 3\,120 \text{ } \text{seconden}\)
Dus \(172\,800 + 54\,000 + 3\,120 + 11 = 229\,931 \text{ } \text{seconden}\)

\(117\,817 \text{ } \text{seconden} = {117\,817 \over 24 ⋅ 60 ⋅ 60} = 1{,}363... \text{ } \text{dagen}\)
\(0{,}363... \text{ } \text{dagen} = 0{,}363... ⋅ 24 = 8{,}726... \text{ } \text{uren}\)
\(0{,}726... \text{ } \text{uren} = 0{,}726... ⋅ 60 = 43{,}616... \text{ } \text{minuten}\)
\(0{,}616... \text{ } \text{minuten} = 0{,}616... ⋅ 60 = 37 \text{ } \text{seconden}\)
Dus \(1 \text{ } \text{dagen} \text{,}\) \(8 \text{ } \text{uren} \text{,}\) \(43 \text{ } \text{minuten}\) en \(37 \text{ } \text{seconden} \text{.}\)

\(1 \text{ } \text{anderhalf uur} = 90 \text{ } \text{minuten}\)