Significant Figure (Angka Penting)

A few days ago, I had an awkward moment..

On that day, I did not know that my classroom was used by eleventh grade students for studying physics. So after praying at mushola,  I just came into the classroom without knocked the door when they were studying. They were looking at me and said, "Pak Bennniiiiiii" (with a strange intonation), and I just showed them my poker face, LOL.. 

NO.. it is not the awkward moment.

Here is the awkward moment begin..

I sat on my chair before one of the students asked me a "difficult" question, he asked, "Mr. Benni, how many significant figure are there in the number 230?" 

(I said that it was a "difficult" question because I totally forgot the rule of significant figure and I was wondering, why don't he asked Ms. X that was teaching him). 

Then I replied,"it's three significant figures" (I thought that the 0 is also significant). The student then shouted loudly, "Ms. X, my answer is true, it's 3 significant figure, Mr. Benni told so. Why do you keep saying my answer is wrong?"

ZZzzz.. I felt so nervous because Ms. X is absolutely knew more than me as she was the physics teacher. Ms X said to him," Your answer is incorrect, it is two significant figures, you can find the source from Erl*ng*a physics book 10th grade". Hmm, I thought that Ms. X was ready for debating with me, however, I felt so horrified with her. So I chose to get out of the classroom. No.. no..no.. It is not either for running out of my problem or not brave enough to take responsibility from what I had said. I went to the computer lab, and search about the significant figure.

I found that my answer was right. It was written like this:

1. Angka yang bukan nol adalah angka penting,
   misal : 14569 = 5 angka penting, 2546 = 4 angka penting
2. Angka nol di sebelah kanan tanda desimal dan tidak diapit bukan angka nol bukan angka penting,
   misal : 25,00 = 2 angka penting
   25,000 = 2 angka penting
   2500 = 4 angka penting ( mengapa ? sebab tidak ada tanda desimalnya)
   2500,00 = 4 angka penting
3. Angka nol yang terletak di sebelah kiri angka bukan nol atau setelah tanda desimal bukan angka penting.
   Misal : 0,00556 = 3 angka penting
   0,035005 = 5 angka penting (karena angka nol diapit oleh angka bukan nol)
   0,00006500 = 4 angka penting
4. Angka nol yang berada di antara angka bukan nol termasuk angka penting. Misal : 0,005006 = 4 angka penting

however, in the last word, the writer of the site gave a note like this:

Berdasarkan buku Schaum Fisika edisi 8 karangan Bueche (1989) bilangan nol (0) kadang-kadang dinyatakan sebagai angka penting kadang pula bukan angka penting karena angka nol hanya menunjukkan letak tanda koma sebagai tanda desimal. Misal : mineral beratnya 8900 gram belum menunjukkan dengan pasti ketepatan penimbangannya. Karena itu ada aturan yang menyatakan 8900 gram hanya memiliki angka 8 dan 9 yang dinyatakan penting (2 angka penting) akibatnya 8900 gram ditulis dengan eksponen sebagai 8,9 x 10^2 gram. Seandainya kemampuan alat ukur mampu mengukur hingga puluhan maka ditulis menjadi 3 angka penting sebagai 8,90 x 10^2 dan jika benda mampu diukur hingga ratusan gram maka hasil pengukurannya ditulis sebagai 8,900 x 10^2.

From this note, I concluded that Ms. X was not incorrect too. Hmm, actually I did not know what to say but I came back to the class and told everybody that I was wrong. The reason is simple, I did not want to make my professional relationship with Ms. X as a teacher broken. I wanted to keep her dignity in front of her students, hoho.. 


That's a little story of me.. At least if I forget about this significant figure again, I just need to open my blog and see this post, hehe..
Oh, by the way I got the information from here. If you have information about significant figure that is more valid, you can post the link into comment box.. Thank you for reading my post, see you..