Rekenen met datum en tijd

Aangezien \(t = 0\) overeenkomt met 1 januari, komt \(t = 269\) overeen met \(270 \text{ } \text{januari} \text{.}\)

\(270 \text{ } \text{januari}\)
\(\text{ } = 270 - 31 \text{ (januari)} = 239 \text{ } \text{februari}\)
\(\text{ } = 239 - 28 \text{ (februari)} = 211 \text{ } \text{maart}\)
\(\text{ } = 211 - 31 \text{ (maart)} = 180 \text{ } \text{april}\)
\(\text{ } = 180 - 30 \text{ (april)} = 150 \text{ } \text{mei}\)
\(\text{ } = 150 - 31 \text{ (mei)} = 119 \text{ } \text{juni}\)
\(\text{ } = 119 - 30 \text{ (juni)} = 89 \text{ } \text{juli}\)
\(\text{ } = 89 - 31 \text{ (juli)} = 58 \text{ } \text{augustus}\)
\(\text{ } = 58 - 31 \text{ (augustus)} = 27 \text{ } \text{september}\)

Aangezien \(t = 0\) overeenkomt met 18 mei 2018, komt \(t = 65\) overeen met \(18 + 65 = 83 \text{ } \text{mei} \text{.}\)

\(83 \text{ } \text{mei}\)
\(\text{ } = 83 - 31 \text{ (mei)} = 52 \text{ } \text{juni}\)
\(\text{ } = 52 - 30 \text{ (juni)} = 22 \text{ } \text{juli}\)
Dus bij \(t = 65\) hoort 22 juli 2018.

5 augustus 2022 is \(t = 0\)
31 augustus 2022 is \(t = 31 - 5 = 26\)
30 september 2022 is \(t = 26 + 30 = 56\)
31 oktober 2022 is \(t = 56 + 31 = 87\)
20 november 2022 is \(t = 87 + 20 = 107\)

\(t = 28{,}7\) valt dan in \(\text{1963} + 28 = \text{1991} \text{.}\)

\(\text{2012}\) komt dan overeen met \(t = \text{2012} - \text{1991} = 21 \text{.}\)

De maand november heeft \(30\) dagen.

De \(6\)e maand van het kalenderjaar is \(\text{juni} \text{.}\)

Op \(t = 9{,}447\) is het \(9 \text{ } \text{uur}\) en \(0{,}447 ⋅ 60 = 26{,}82 \text{ } \text{minuten}\) later dan \(\text{3:00} \text{ } \text{uur} \text{.}\)
Het is dan dus \(\text{12:26} \text{ } \text{uur} \text{.}\)

Om \(\text{5:48} \text{ } \text{uur}\) is het \(5 \text{ } \text{uur}\) en \(48 \text{ } \text{minuten}\) later dan \(\text{0:00} \text{ } \text{uur} \text{.}\)
Dat is dus bij \(t = 5 + {48 \over 60} = 5{,}8 \text{.}\)

\(17{,}8 \text{ } \text{dagen} = 17{,}8 ⋅ 24 \text{ } \text{uren} = 427{,}2 \text{ } \text{uren}\)

\(198 \text{ } \text{minuten} = 198 : 60 \text{ } \text{uren} = 3{,}3 \text{ } \text{uren}\)

\(0{,}83 \text{ } \text{jaar} = 0{,}83 ⋅ 12 = 9{,}96 \text{ } \text{maanden} \text{,}\) dus \(3{,}83 \text{ } \text{jaar} = 3 \text{ } \text{jaar}\) en \(10 \text{ } \text{maanden} \text{.}\)

\(9 \text{ } \text{minuten}\) en \(58 \text{ } \text{seconden} = 9 + {58 \over 60} = 9{,}966... \text{ } \text{minuten} \text{.}\)

\(9 \text{ } \text{dagen} = 9 ⋅ 24 ⋅ 3\,600 = 777\,600 \text{ } \text{seconden}\)
\(2 \text{ } \text{uren} = 2 ⋅ 3\,600 = 7\,200 \text{ } \text{seconden}\)
\(19 \text{ } \text{minuten} = 19 ⋅ 60 = 1\,140 \text{ } \text{seconden}\)
Dus \(777\,600 + 7\,200 + 1\,140 + 3 = 785\,943 \text{ } \text{seconden}\)

\(202\,484 \text{ } \text{seconden} = {202\,484 \over 24 ⋅ 60 ⋅ 60} = 2{,}343... \text{ } \text{dagen}\)
\(0{,}343... \text{ } \text{dagen} = 0{,}343... ⋅ 24 = 8{,}245... \text{ } \text{uren}\)
\(0{,}245... \text{ } \text{uren} = 0{,}245... ⋅ 60 = 14{,}733... \text{ } \text{minuten}\)
\(0{,}733... \text{ } \text{minuten} = 0{,}733... ⋅ 60 = 44 \text{ } \text{seconden}\)
Dus \(2 \text{ } \text{dagen} \text{,}\) \(8 \text{ } \text{uren} \text{,}\) \(14 \text{ } \text{minuten}\) en \(44 \text{ } \text{seconden} \text{.}\)

\(1 \text{ } \text{etmaal} = 24 \text{ } \text{uren}\)